how to add OID 2.5.4.97 to Subject field of certificate?

[erdnbat]

I want to create CSR with following subject distinguished name "CN=TEST,O=TEST, ..., OID.2.5.4.97=1234", but after calling Pkcs10CertificationRequestDelaySigned, it ignores OID. What kind of extentions do I need. How to add OID to CSR? Thank you.