I looked in the FAQ list and saw nothing about it, but the ability Kitsune's charm allows you to cast Charm person a few times a day and while it tells how to calculate your caster level it doesn't designate a casting stat.
The saving throw (if any) against a spell-like ability is 10 + the level of the spell the ability resembles or duplicates + the creature's Charisma modifier.
It defaults to charisma
Oh ok then.