Don’t worry guys, have found the answer myself.
I was assuming that to provide context there would be an API call/overload etc. The reality, of course, is ridiculously simple, you just supply the context in the body of the query, the following is a typical RAG template query e.g:
"Answer the question based on the context below. If you can't answer the question, reply, "I don't know". Context: apples can go in the red bin. pears can go in the red bin. grapes can go in the red bin. plums can go in the blue bin. Question: list everything that goes in the red bin."
Regards.