There are two methods to sign a PDF using FNMT’s Digital Certificate for Natural Persons:
- Using Autofirma application
- Digital sign from Adobe Acrobat
Methods to sign a Digital Certificate
Method 1: Using Autofirma application
Follow the instructions from this video tutorial.
Step 1: Open Autofirma application
Open Autofirma application. If you have not installed it on your computer, you can download it from here.
Step 2: Drag and drop PDF file into Autofirma
Drag and drop PDF file into the bottom part of Autofirma
Step 3: Sign PDF
Mark options like “Hacer la firma visible dentro del PDF” and “Insertar una marca visible dentro del PDF“.
Click on “Firmar fichero“.
Select the area of the document where you want to add the signature.
Select format options, like font, size, etc.
Select certificate to sign document.
Select a folder to save the signed file.
Method 2: Digital sign from Adobe Acrobat Reader
Step 1: Ensure you have the last version of Adobe Acrobat Reader installed
Latest version of Adobe Acrobat Reader application is Adobe Acrobat Reader DC.
Go to Menu Bar > Help > Check for updates to ensure Adobe Acrobat is up-to-date.
It is recommended to use Windows to avoid compatibility issues.
Step 2: Unhide the certificate functionality in Adobe Acrobat Reader DC
Open PDF file with Adobe Acrobat Reader DC.
Locate the tools pane on the right hand side. If it is hidden, go to Menu Bar > View > Show/Hide > Tools pane or press Shift + F4.
Use the search box on the top of the tools pane to look up for “Digital sign”.
Alternatively, you can also go to “More tools” in the tools pane and open “Certificates”.
Step 3: Sign the PDF document
“Certificates” bar will appear right below the menu bar. Click on “Digitally sign”, draw a rectangle in the region of the document where you want to put your signature and then select the digital certificate that is installed in your computer.
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External references
- Unidad de Coordinación de Procesos Económicos de la Universidad Autónoma de Madrid; “Firmar un PDF con autofirma“; Universidad Autónoma de Madrid (Spanish)