I use injectable Ivomec at 0.1 cc per 2 pounds of body weight, the only reason I use it is if ear mites or fur mites make an appearance in my rabbitry. With rabbits under 12 weeks old (if they are not in my meat pen) I will apply it topically between the ears at the base of the skull if treating for ear mites or between the shoulder blades if treating for fur mites.
Ivomec does not treat the intestinal parasite varieties most common to rabbits: whipworms, wireworms, and tapeworms. For these, SafeGuard liquid goat dewormer is effective (and much safer than Ivomec), given orally at 0.1 cc per pound of body weight, so a 10 pound rabbit gets 1.0 cc (cc and mL are interchangable). SafeGuard needs to be given 3 days in a row.