Patronymic from "Никита" is a wee bit different from other Russian patronymics. Usually you add endings "евич", "ович" to men patronymics and "евна", "овна" to women patronymics... But to patronymic from the name "Никита" you should add "ич" (in the case of men's patronymics) to get "Никитич" and "ична" (in the case of women's patronymics) to get "Никитична".