Trying to program a GE univ remote for an RCA

Such a code may or may not exist. If none of the codes listed in your owners manual work (you didn't list a model number so I can't give you specifics)you have 3 options. 1) Contact GE and see if they have additional codes not listed in the manual. 2) Contact RCA and see if the have additional codes to try. 3) Purchase a 3rd party remote that works with both devices.