This link should get you to the correct drawings for you RV:
There are 8 different layouts, depending on options you have, so I will let you choose.
But a major point is often how to set the switch as well as set the input on the TV, often through a menu. Over the air is likely to be different setup on the TV than cable.
I normally think of the switch on the plate mentioned as powering an amp for the antenna. Do you have a set of LED on the mount on the ceiling where you rotate the antenna? How to turn the antenna and set any gain from the amp is likely to take a bit of reading on your specific amp (if you have one!)
My basic idea is that with the switch on, LED lit, the OTA cables are set to TV, set TV to antenna or whatever your TV calls it, let it scan and then there should be programs there if close enough. For cable, turn switch off, set TV input to cable and should see that!
But do check that your cables run like one of the drawings. Not a very handy thing for RV as we used to be able to set a TV to some channel we knew was in the area and swing the antenna around to get the best picture without the added time delay of scanning for channels that may not be in that area at all.
Electronic advances often do come with a downside!