Formatting .pdf documents with digital signature block

I have created a 2007 MS Access database that exports reports to .pdf format. The reports look great and all works well. The issue I have now is finding a way to automatically apply to a signature block to the reports after they are created. Is there some sort of code format or text I can add to the report prior to it being exported to a .pdf file where Adobe will recognize it as a digital signature block, and create a digital signature block on the form? Several of these forms will be created daily and it would not be productive to manually add signature blocks to every single report.