I got this info from a different board & wanted to post it here;
Many people here will have a different opinion on this subject - here's mine: If you are comfortable with injectables - go for it! It provides a more precise dosage and you can treat the individuals with the problem as a opposed to mass medicating. I use Ivomec 0.27% injectable for feeder pigs. It won't be cheap, but it will last forever if stored properly. (All of the Ivermectin products are expensive, but worth it for their safety and effectiveness.) The dosage is 0.066cc/lb. I know this sounds impossible, so let me simplify - I give 0.075cc/bantam. If you have a 1cc syringe with 10ths (.10, .20, .30 and so on), there will be tiny tick marks between each tenth. Inside of the first (lowest dosage) .10, you can see where the half-way mark would be (0.05), and then determine about where the 3/4 mark (0.075) would be. It's a tiny dose. If you go past the 0.10, you've gone too far and figured wrong for a bantam. If you have standard birds, determine their weight and take the 0.066cc/lb dose and multiply it by the number of lbs of the bird for the accurate dosage. The injection should be made subcutaneously (just under the skin), at the back of the neck. If you're not sure, I or the board can help before you do it.

For scaley leg mite, as prescribed by PRVs in a University Poultry Lab, it's necessary to redose 3 days later.

If you want to 'prevent' scaley leg from coming back, you can use the flea and tick drops sold for cats and dogs at any store (the one-month drops that are normally run down the center of the back of the animal in a 'bead'), and just run a tiny bead right down the top of the center toe on each foot. Works like a charm.