Hi,
I have over 10 years experience in digital signature.
I know what exactly you need, I can build a CSP driver for you. The CSP driver is a bridge between 3rd applications (adobe reader, foxit reader,…) and yiur centralized certificate (remote signing).
I have built CSP driver like your requirements, so I can help you do it fastest.
I can provide demo for prove of concept (POC).
Contact me if you interested!
Thank you!