Mary:
I'm not that familiar with rabbit worms, since all mine are on wire and never get exposed.
However, I worm cattle with Ivermectin (formerly Ivomec, now sold under a number of brand names). I use the pour-on formula calibrated to work at one milliliter per 22 pounds of animal. This is poured on the animals back (I pour it between the shoulder blades) and works for about a month.
I use it in rabbits to eradicate ear mites. It does the job in one dose. A 7-pound doe will get just about a third of a CC. If I want to be exact about it I measure the dose with a tuberculin or diabetes syringe. The ivermectin is a very forgiving drug, tho and I usually just drop ten or so drops on the rabbit's back. Other people here use the injectable, dropping it on the animals skin also. The injectable is much more potent so that one or two drops is plenty.
The stuff is fairly expensive, but many feed and animal supply stores will sell it in syringes by the dose for cattle at about 75 cents per CC.
Ox