It depends on the “Limitations” noted on your certificate. If the authority of the OICNW is limited to 200 GRT, then you can’t use it to serve as RFPNW on a vessel greater than 200 GRT unless your certific ate also has RFPNW on it without a tonnage limit.
You have a an STCW certificate (a separate certificate with your picture on it, not words on your license) for OICNW not more than 200 GRT?? What REC did you get it from?