Obtain RIC from RQID

You can use CodeCreator app in Eikon to browse the data items (or fields) and construct a Python code sample that retrieves these data items.
What is RQID? I don't think I've come across this abbreviation previously.

I'm afraid I cannot answer your question without knowing the context. What is RQID? What kind of identifier is it and what assets does it identify? There's no one universal field that would give you the RIC for any kind of input. Not to mention that it's possible there are no RICs for whatever it is that RQID identifies. Probably the most widely applicable field that returns a RIC is TR.RIC, but I cannot possibly tell if it'll work for your use case without understanding what the use case is.