I usually find the RIC on this search page.
Tom
Is your query about how to determine what RIC to use to request specific data ?
If no: please give us more detail about what you are trying to achieve.
If yes:
If you have access to an Eikon application, you can open a quote windows (press the F4 key to open one). Then either:
If you don't have an Eikon application you can use the speed guide available under the Tools section here.