From the SRD:
Weapon Finesse [General]
Prerequisite: Proficient with weapon, base attack bonus +1 or higher.
Choose one light weapon. Alternatively, the character can choose a rapier, provided the character can use it in one hand, or a spiked chain, provided the character is at least Medium-size.
The only weapons with size restrictions are the rapier and the spiked chain.
I almost wish I'd chosen a Halfling Rapier instead, anyway - 1d4 weapon that has an 18-20 crit range. But it's a feat to use it (exotic), so....