Mix 4ml F10 SC in a litre of water (dilution ratio 1:250) and nebulize the reptile for approx 30 - 40 mins every day until the RI is cleared. If its a snake, after nebulizing hold it head down and clean any mucus from the mouth with an ear-bud. If you see no improvement after a week or so, go to a vet. Nebulizing works if you catch RI early however if its severe you may also need antibiotics. You should also check your environment is set up correctly - temps, humidity, etc.
MAKE SURE you are NOT using the F10 SCXD!!!!!