Just so that I am clear in regard to your question: Are you asking about RFID on the Workabout Pro 4? And the EMDK compatability for the RFID technology on WAP4?
RFID on Psion Workabout Pro platforms is not accessible from the EMDK or Data Wedge at this time.
In order to use RFID technologies on Workabout Pro 4, you need both the Psion MDSDK and the Appropriate RFID SDK for the Module installed on the WAP4.
More questions about the Psion implementations for RFID can be asked in the forums at Ingenuity Working.