For scaly leg mites I dip the feet in a permerthin solution (warm solution) once a day for seven days. Stop for seven days and reevaluate your chickens feet. Retreat for seven days if needed. Evaluate your chicken's surroundings and clean up where needed. Treat the area with insecticide, too.
I do not like to apply Vaseline as that creates an environment where bacteria can thrive and cause a severe skin infection. If the chickens feet are already infected you can paint the feet with a betadine solution when dry.
Do not eat the eggs from treated chickens for 30 days.
Good luck! I hope this helps!