I assume you mean the GFCI outlet.
Usually it is in the bathroom or kitchen. It may be in the fridge compartment where the fridge plugs in (assuming an absorption fridge) or possibly the outside outlet or possibly one of the other outlets in the RV. It is also possible that they decided to use a GFCI circuit breaker rather than a GFCI receptacle; this would be identifiable by the test button on the breaker.
I think I read here of one RV where it ended up being behind the TV, not the most convenient by far.