All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
It is permissible for a husband to kiss his wife’s foot as a way of foreplay, but he should not lick it as there is no need for doing so because this may lead to harm.
As regards doing so with non-Mahram women, then it is not permissible to kiss their feet or touch any part of their body in principle.
With regard to kissing the feet of Mahram women as an act of kindness or affection when one comes back from travel or when leaving, then this is permissible provided that one is safe from temptation.
Allaah Knows best.