LPT is correct about certain antiparasitics being lethal to rabbits, especially Fipronil. So we always warn against the use of Fipronil.
Ivomec is ivermectin though, and that is one of the bunny safe antiparasitics. We can’t tell you to use it, we are not vets. The best thing is to see a vet and get a prescription for revolution (selamectin, a compound derived from ivermectin).
Here is a chart of safe antiparasitics, from Medirabbit, a trusted source: http://www.medirabbit.com/Safe_medication/Anti_parasitics/safe_antiparasitic.htm
For ivermectin it says it can be given subcutaneously (injection under skin) or per oral (by mouth).The correct dosage is important, so do the maths very carefully.
I googled around a bit and found mentions of it being just as effective if you drip a couple of drops (for a Nethie I’d restrict it to one drop) on the skin between the shoulderblades, but I found no really good, trusted source to confirm that, just anecdotal evidence from bunny owners.
You could ask on other forums as well f ex Rabbits Online. They have a health and wellness sectrion where there’s a whole thread about risks with ivermectin overdose. You might be able to find more useful info there and bun owners who have used generic ivomec themselves. http://www.rabbitsonline.net/index.php