I put 'you are tiny' in the keyboard section... looks like I can't say my friend is tiny, but at least I can say they're small.
machqu' might be appropriate for "tiny".
Im going to say this to my short friend
bIrun. "You are short." might be better for that -- mach is probably better for overall smallness while run is specifically for someone who is short of stature.
(Mnemonic: he's a runt.)