Cod Liver Oil medium source getting fluorine.
Or
make soup: first, buy bone-joint of young animal.
add greens
liquid can be of water or of some kind of broth
boil
Slowly simmer your soup
Time: To do is 6 hours
(Caution): fluorine will rise quickly to the ceiling if one cooks soup fast.
Or
buy Seagrass because where grass grows water is green with fluorine.
Or
Raw pastaschio nuts good in fluorine (cannot remember if this one definite)