It's generally accepted that the oldest Latin inscription is on the Praenestine Fibula:
MANIOS MED FHE FHAKED NUMASIOI
The verb here seems to be an old reduplicated perfect of faciō, equivalent to Classical fēcit.
I know I've seen this spelling, <FH> for
/f/, before—but I can't seem to remember or find the context. So: when and where was this spelling used? Was it common in very early Latin, or in another nearby language? And when did it die out?