The Magic Trait "Magical Knack" adds +2 to caster level, so long as it does not exceed your Hit Dice.
I have an elven Ftr 2 Rgr 4.
On her own she has a caster level of 1 (Rgr -3).
Magical Knack should increase that to 3.
She can select 1 spell only, but as I try out different spells, I seeher spells calculated as if lvl 5.
E.g. Call Animal increases from 1hr to 5hrs.
pathfinder core supplements ruleset