We’ve not got a ROMP, but we do have a couple of Womanizers. For those, I’d say position is key. There seems to be a sweet spot that takes those gentle put-puttering taps, and turns them into something orgasmic. 
It can take a bit of practice though, so it’s worth having a few goes before deciding it isn’t for you. Obviously not all toys suit everybody, so it may be that it just isn’t your kind of stimulation type, but fingers crossed you can get it working for you. 
There’s also the Womanizer - did it work? topic which you may find an interesting read while you wait for more replies. 