I added a Scribbled Rabbitfish to my 120gal with an established One Spot Foxface with no real issues.
Something else to consider is what other fish you have in the tank. Rabbitfish tend to be shy until they feel confident enough with the other tank mates. If they get harassed, the will stay hidden. You will want to make sure that the fish gets something to eat. Once confident, they will stand up for themselves and be a great addition to your tank.
That's my experience.