You didn't give much detail, but a typical RV fridge such as a Dometic, will use around 300 watts on AC. That translates to around 23 amps from your battery or DC system using an inverter. That's about equivalent to leaving two sets of headlights on. Probably OK if engine is running, maybe not if engine is shut down.
(These are "rule of thumb" estimates.)
2000 Bounder 39Z DP
Recently retired our beloved '88 Chieftain 27
<<the one the grand kids grew up in>>