How to Digitally Sign a PDF Document?

(For the latest PDF files Merger Software please have a look at the top of the left margin, inside the red box.) Now this basic signature manager is ready in Codes For Us PDF Merging utility, beta_6_3 (here). It is yet far from being complete. You notice that to use it one needs a PFX (PKCS#12) to have ready somewhere either self-signed or CA signed. I have a humble tweak GUI to create that PFX at home using self signature, available in download area. My 'uber-geek' friend Grant Hardy (who is a microwave engineer and has implemented Messiah's Calendar [he sleeps on a Smith's Chart at nights]) has promised to give a hand to meet our promised milestone around the Christmas, for further features to be accompanied (e.g., a password remover is ready now done by him, a password unlocker he is also interested as a matter of algorithm tests, not by using a brute force). With this Signature Manager one cannot put her seal emblem on the digital signature. It is just a standard digital signature of PDF documents as it is defined. The Water-mark utility provided by Codes For Us might meet that demand, if one is interested. But people are interested to have emblem next, or as under-layer to their digital signature, too. Hence, I try to add that feature, later to the manager (04/Jan/11: Now the feature is added)). I hope you enjoy this version for now.
Update 04/January/11: Now notarize PDF with external timestamp, seal emblem under-layer, and few other features are included. Codes For Us PDF Merging utility, 01/March/11, beta_6_7 (here).
Update 05/March/11: Now with a visual help page (here).