Your country? You listed Miami as your city, and there are rabbit vets on that list for Florida and Miami Dade County. Are you not in the US?
A lower dose is safer, but still needs to be in the effective dosage range, which is 0.2-0.4mg/kg for fur mites and 0.4mg/kg for mange and ear mites. It's not necessarily the dose that's the problem, unless you have a breed that has a higher risk of being sensitive to ivermectin because of the MDR1 gene (BEW, Dutch, Vienna carriers), it's when the dosage is calculated incorrectly and too much is given.
I don't recommend doing this yourself, but if you're still going to do it, it's very important to make sure the correct dose is exactly calculated for the weight of your rabbit. The recommended dose for mites is 0.4mg/kg(0.18mg/lb), which when giving the 1%(10mg/ml) ivermectin injectable solution(I would never recommend using the large animal paste), would be 0.04ml per kg of body weight(0.018ml/lb). It's essential that the mg of dosage isn't confused with the ml of the amount being administered. Otherwise an OD will occur.
I will draw the injectable solution up into a 1ml syinge(the appropriate dose), then remove the needle and give by mouth. And this is a miniscule amount, usually less than a drop and less than one tenth
of a ml/cc for a rabbit under 5 lbs.
In Europe there is a topical spot on ivermectin for small animals(including rabbits) called Xeno 450, and this will have instructions for application. If you aren't in the US and have Revolution/Stronghold topical spot on available to you OTC, that would be my first choice for treating mites as it's a little bit safer for sensitive rabbits and less likely to cause an OD. The recommended dosage is 18mg/kg for rabbits.
Medirabbit: ear mites, revolution dosage
Medirabbit: fur mites
Medirabbit: sarcoptes mange