This entry has been published on 2012-05-14 and may be out of date.
Last Updated on 2012-05-14.
Software602 Print2PDF Free is the only free PDF printer software I found with the ability to sign PDF documents.
You have to install your certificate in the common Windows certificate store and you are ready to sign with it.
PDFCreator also has a signing function, but you always have to enter the cert key before every new PDF signing.