Hi,
I think in your case you are looking at the GOS functionality of archiving a PDF in the DM repository. The following will give you starting steps:
If that is the case. The below wiki will give you a better idea also
http://wiki.sdn.sap.com/wiki/display/Snippets/Save+SmartForms+OTF-output+as+GOS+PDF-attachment
Cheers,
Arindam