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How to sign a PDF

They asked you to sign a digital document in PDF format but you don't know how to do it? Don't worry, following this guide you will discover all the methods you can use for sign a PDF document both using a printer and using digital tools to apply the so-called electronic signature, i.e. applying your scanned signature directly on the document to be signed in digital format, so as not to waste paper and ink as well as save time.

How to add the signature to a PDF

Differences between electronic signature and digital signature

There is a big difference between electronic signature and digital signature:

  • The electronic signature the signature that you can apply by scanning or writing on a special Wacom device, has legal but not authenticated value, therefore it can be repudiated and discuss its authenticity.
  • The digital signature instead the signature certified by a third party which has all the characteristics that an important signature must possess (i.e. authenticity, integrity and non-repudiation).

In this guide I will show you how to put an electronic signature on documents, so make sure that signed documents are not so important as to require an authenticated signature.If you want to deepen the discussion on digital signature and how to obtain it, I refer you to reading our dedicated guide:

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Print and scan the document

The simplest method is within everyone's reach by simply printing the document or sheet in which you require the signature. Open your favorite PDF reader on PC and press the Ctrl + P keys (or click on the printer symbol) to start the print (alternatively you can go to the menu File> Print).

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The printer connected to the PC or connected via the network will be found, so all you have to do is start printing. As soon as the ready sheet signs in the designated area with a black pen and get ready to scan the sheet again (this time with the signature!).

Open the tool on your PC Windows fax and scanner, looking for it in the Start menu.

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Click on the top left corner New digitization and save the scan. The scanned sheet will be in image format; to be able to convert it to PDF or to add this image to a PDF already present, all you have to do is go to the SmallPDF website, in the section JPG to PDF.


<img class = "lazy lazy-hidden aligncenter size-full wp-image-36688" data-lazy-type = "image" src = " /Convertire-JPG-in-PDF_risultato.jpg” alt=”Convert JPG to PDF” width=”793″ height=”645″ data-lazy-/>

Upload the image file using the "Choose file" button or simply by dragging it inside the yellow box; the site will do all the rest, making you download your new signed document in PDF format.

Is the signed sheet part of a larger document? In this case you just have to read the rest of the guide to be able to edit even the longest PDFs.

Personal signature scan

If you want to edit the original PDF document directly you will first need to get your electronic signature. Take any blank sheet of paper and write your signature on it, then use a scanner and the program. Windows fax and scanner to acquire your signature in electronic format. Once you have scanned the entire sheet with the signature, you can also crop the latter using a free photo editing program such as GIMP, available below:


Using the crop tool, you can delete most of the unused sheet and keep only the part of the sheet that contains your signature.

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Once you have obtained this scan of your personal signature, you can apply it in different ways to your PDF documents, as I will explain in the following paragraphs of the guide. Once finished, all you have to do is save the changes to the signature sheet by clicking on File> Overwrite Image.

From now on you will have an image with your electronic signature ready to be applied on PDF documents.

Sign a PDF on PC


To sign a PDF document on a PC, simply open SmallPDF and use the section Edit PDF, reachable below.

LINK | Edit PDF with SmallPDF

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Click on "Choose file" or drag the PDF document to be edited in the box, then add the image file with the signature using the tools provided by the site.

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At the end it will be sufficient to save the file and download it in PDF format.

Alternatively, you can use the PDF Signature section, always offered by SmallPDF, in order to correctly apply the signature to the document.

LINK | Sign PDF with SmallPDF

<img class = "lazy lazy-hidden aligncenter size-full wp-image-36693" data-lazy-type = "image" src = " /Firma-PDF-con-firma_risultato.jpg” alt=”Sign PDF with signature” width=”793″ height=”637″ data-lazy-/>

Drag the document into the pink box or use the "Choose File" button to upload the PDF to be signed. In the next screen you will have several methods to sign your PDF.

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You will have:

  • Draw: just use the mouse or trackpad to generate the signature.
  • Upload: to load the image file with the signature.
  • Room: to take a photo of your signature via Webcam

Choose one of the proposed methods and sign the PDF document; at the end the site will let you download a version of the PDF with your signature affixed correctly.

Adobe Reader DC

If you want to use a program to sign a PDF you can use the most famous PDF reader for the purpose:Adobe Reader DC. If you have not yet downloaded this program for your PC from the following link.

DOWNLOAD |Adobe Reader DC

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On the download page remove the ticks on the unnecessary programs and extensions (red arrows) and finally click on ?Install now?. At the end you will have the Adobe PDF reader installed on your PC. Now use this program to open the PDF that you want to sign, then go to the right side menu and click on "Fill in and sign".

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A new bar will appear at the top; to sign the document, click on the fountain pen icon (Signature). A drop-down menu will appear where you can choose to add a signature or add initials.

<img class = "lazy lazy-hidden aligncenter size-full wp-image-36697" data-lazy-type = "image" src = " /Aggiungi-firma-Adobe-PDF.jpg” alt=”Add Adobe PDF signature” width=”602″ height=”320″ data-lazy-/>

Click "Add signature" to see the screen appear with all the signature tools offered by Adobe Reader.

<img class = "lazy lazy-hidden aligncenter size-full wp-image-36698" data-lazy-type = "image" src = " /Strumenti-per-firma-Adobe-PDF_risultato.jpg” alt=”Adobe PDF signature tools” width=”793″ height=”395″ data-lazy-/>

You will have three tools to sign your PDF:

  • Type: just type your name and surname on the keyboard.
  • Draw:you can draw your signature using the mouse, trackpad or any Wacom device.
  • Image: you can upload the photo image of your signature.

Choose the best tool and sign the PDF document using the "Apply" button.

Advice: leaving the checkbox on "Save signature" Adobe will remember your signature for future use.

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Sign a PDF on smartphone or tablet

Do you want to sign a PDF using your smartphone or tablet? In this case no one beats the practicality of Adobe Acrobat Reader, the best mobile PDF reader. You can download the app for free from one of the following links.

DOWNLOAD | Adobe Acrobat Reader (Android)

DOWNLOAD | Adobe Acrobat Reader (iOS)

Once the app has been downloaded, simply open the PDF document with it and use the "Compile and sign" option, as already seen on a PC.

<img class = "lazy lazy-hidden aligncenter size-full wp-image-36699" data-lazy-type = "image" src = " /Adobe-Acrobat-Reader-firma-da-mobile.jpg” alt=”Adobe Acrobat Reader signs from mobile” width=”494″ height=”626″ data-lazy-/>

Also in this case it will be possible to choose how to add the signature, using an image already created or using the touch screen of the mobile device to generate the required signature.