TinaMarie - Most RV refridgerators run on AC or Propane so you really do not need a generator in most situations. Just about any small portable will be enough to charge the batteries during the daylight hours.
What type of RV are talking about here and what asside from the refridgerator are you concerned about?
Are there budget contraints? The ones Richard has mentioned while they are very nice can be quite pricey $600 to $1000 each.
If you are not looking to run an AC unit or multiple high wattage appliances this one from Harbor Freight for $99 may be all that you need.
800 Rated Watts/900 Max Watts Portable Generator