Follow these steps to digitally sign a document with Acrobat Reader DC:

• Open the document you want to sign.
• Click ' tools' .
• Click 'Certificates'.

• Click 'Digitally sign' at the top of the document.

• Select a zone in the document where you want to place the signature.
• Select a signature certificate.

• The program now asks you to save the document.
• You are then asked to enter your PIN code.
• Enter your PIN code and click 'OK'.

The document is now signed.

Note: In order to place an electronic signature using Acrobat Reader DC, you need a security module. Acrobat Reader DC uses the eID minidriver as security module as standard, but you can choose to use the 'PKCS#11' module instead.

Have you followed all the steps yet are unable to sign your document? Then you can read how to solve this here.