Imagemagick Ghost Script Expert for pdf

We are looking for expert who can help resolve issues we are facing in converting images into pdf after digital signatures and other fields are placed on pdf image. We are developing digital signature software similar DocuSign, hello sign etc We are using Imagemagick, ghost scripting under ubuntu environment. User uploads a contract or another pdf document, we place some text boxes, check boxes, dropdown controls , digital signs once completed we convert document back to pdf.