6 letter words:
fritts9,
5 letter words:
first8,
frits8,
fritt8,
rifts8,
4 letter words:
firs7,
fist7,
fits7,
frit7,
rifs7,
rift7,
sift7,
stir4,
tits4,
3 letter words:
fir6,
fit6,
ifs6,
rif6,
its3,
sir3,
sit3,
sri3,
tis3,
tit3,
2 letter words:
if5,
is2,
it2,
si2,
ti2,