medikit in the combat window has a button along the bottom of the screen when a person is selected. They have to have one equipped from the caravan "equipment" menu. Once you have it selected, you have to select a "target" like you would for a weapon. You can either select yourself, or a buddy next to the selected charactor
i wasn't offended so much as irritated at how hard it got after two levels. not worth playing twice, and barely worth playing once. I sentence you to an eternity of playing your sh**y game...