I don't know what Fns is but in my project I just implemented it myself. It's really not that hard as it seams. I just copied letters as shapes.
I use normal strings like
mytxt$="abcdefghi"
and then access the letters in the loop and bit them on the screen:
i=0
letter.b = peek.b(&mytxt$+i)
block base+letter,......
it works well and I have full control over it and no mess with additional libs