While light-weight pdf readers are a very good alternative to "Adobe Reader" and there are more reasons other than just the bloat to use them, but there are times when a user needs to rely upon the official PDF reader from Adobe. Today we will see how to use free utility software "Adobe Reader X" to digitally sign a document, a digital signature or e-signature is a mathematical encryption technique used to ensure authenticity of a digital message or document. A valid digital signature gives a recipient reason to believe that the message was created by a known sender, and that it was not altered or tampered with in-transit.

How to electronically sign a PDF document using your "Digital Signature" :

1. Open the PDF file/form you need to digitally sign using "Adobe Reader X" or later version.
2. Click the "Tools" option and a new panel will appear with "Sign Document" option.


3. Clicking the "Sign Document" button will open another dialog-box as shown below with all the "Digital Signatures" available on current machine, select the desired signature and and click "Sign".

4. You should now be asked for "PIN" or "Password" needed to sign the document using that identity/digital signature.

5. Once completed your PDF file get signed as shown below.

Voila, you now have a digitally signed document. Government e-forms usually require this type of e-signatures to verify authenticity of the document creator/filler.