Merge XFDF to PDF Form ,Do Digital Signature then send to customer

This is just a screenshot I developed for a customer from RentAcoder.com, what he want is:

• populate data from XFDF(XML FDF, send by customer after they filled the PDF Form) to PDF Form and Create a new PDF with data.
• Signature the new PDF
• send the new PDF to the customer who send the XFDF data.

It uses iTextSharp.

and I am thinking about release it as a useful product.

btw, it does not support Adobe Designer Form(different with Acrobat Form).