Is there any way to programmatically enable Adobe PDF usage rights from .net code ? I\'m using ITextSharp library to fill an XFA Form with XML Data (generated from app), but
The only way to do it programitically is to use Adobe Reader Extension Server. You can review Adobe whitepaper here: http://www.adobe.com/sea/products/server/readerextensions/pdfs/readerextensionsserver_ds.pdf
In the case above you would use iTextSharp to create Pdf document and then use Adobe Reader Extension Server to allow Pdf document to have extended functionality in Adobe Reader.
However, there is a small window that allows you to work with iTextSharp and fill-in already Reader-enabled PDF documents. If you have such Pdf document (Reader Enabled), then you can use iText/iTextSharp to fill in XFA data. You can check example here: http://itextpdf.com/examples/iia.php?id=166
Good luck!