The standard constraint file format does not accept RDC data. I’ve tried in the past to get those who know how to do it to document it, but it hasn’t happened yet.
All the RDC stuff is in the 3.2.1 release but I can’t trace it back to the actual executeable.
There are multiple options referencing “rdc” in the options list: http://www.rosettacommons.org/manuals/archive/rosetta3.2.1_user_guide/options.html
Maybe one of them will work?