You don't, because you can't, sorry. If this is a Roku tv, you will need a remote, but it doesn't have to be true roku remote, any cable remote, or even older universal remote will probably have a code to control it. If you have such remote handy, give me the brand and model of the non-roku remote? I could give you the proper code. Whats the brand of Roku tv is it?
You have RCA remote and want codes for a Roku tv? There so many different RCA universals remotes out there I would need a model number to help. Or you just try Goldstar/ LG tv codes listed for your RCA remote.