Hi Nikhil,
Do you need to protect the PDF or the PDF is still protected?.
If i was you, i would try to divide your problem in hints.
1. To send a PDF in ABAP Proxy - ??? (may be file?) scenario. (Step-by-Step guide to develop Outbound ABAP Proxy from SAP with PDF attachment</title><meta name="descript…)
2. If you need to protect the PDF, do it via java mapping or adapter module. (The previous links will be helpful)
Regards.