It will depend on the size and weight of the boat. It's perfectly possible to ski behind a small inflatable with a 25 hp outboard, but it's not ideal as the skier tends to pull the boat around rather a lot.
Do you know what size boat you want? A small RIB, say 4.5m (15 ft) would be fine for skiing with a 60 hp outboard (in fact a 50 would probably be OK), but a bigger boat would need a bigger engine . . .
Any RIB can have the tubes deflated for storage, saving a foot or two of width, so that won't limit your choice.
There are details of manufacturers in the RIBnet directory. Just a few you might want to consider include Avon, Zodiac, Ribcraft, Ribtec, Valiant or one of the Yamaha packages.
[This message has been edited by John Kennett (edited 13 August 2000).]