Specifically for athletes foot, can u use penlac (ciclopirox)?

No: Penlac (ciclopirox) is made to use on mycotic toenail not on the skin for athletes foot.

Not indicated : Penlac (ciclopirox) is indicated for the treatment of nail fungus or onychomycosis. While both caused by a fungus there are far better options for the treatment of athletes foot.

Not recommended: Penlac (ciclopirox) is an expensive medication. The indication is for a fungal infection of the toenail. Even there, the success rate is very low. The package insert states about 8% so there are much better alternatives. Also, Penlac (ciclopirox) is prescritpion. One can obtain a over the counter medication at the local pharmacy.