Can i put ketoconazole on a fungal infection?

Generally yes: Fungal infections of the skin are very common. They are sometimes referred to a 'ring worm', even though worms and not involved. Ketoconazole is a commonly used anti-fungal medication which may be effective. However, topical medications are not effective for scalp infection; an oral medication is needed. See your doctor if the rash persists.

Yes to skin: Ketoconazole in cream form is appropriate for topical use on the skin for all fungal infections of the skin. It should not be ingested orally nor used in the eyes or other orifices.