I've seen "Keff" used as a nickname for Kefford, which is a surname but could conceivably be used as a first name. I've never seen or heard of Keff / Kef as a female name.
If you want *opinions* on whether Keff / Kef is a good name for a girl, you need to go to the Opinions Board.
♦ Chrisell ♦
All we have to decide is what to do with the time that is given us. - J.R.R. Tolkien.