c# asp.net PDF editor control

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do you guys know of asp.net pdf editor control that would allow users to drag and drop boxes in a PDF file and then they would be sending this pdf over email to another person where this person would be allow to insert signature and text in those boxes that was assign by the sender.what i'm trying to do is create in website where users can send each other PDF forms and allowing them to add signature and notes and more.any open source asp.net pdf editor control or commercial that i should be looking at? i'm not sure if i'm using the correct terms in what i'm trying to develop any help will appreciated.I have looked at this code below in codeproject.com but it's on vb...i'm c# developerhttp://www.codeproject.com/Articles/41933/ASP-NET-PDF-Viewer-User-Control-Without-Acrobat-Re