You can use light armor.
Benefit:When you wear a type of armor with which you are proficient, the armor check penalty for that armor applies only on Balance, Climb, Escape Artist, Jump, Sleight of Hand, Stealth and Tumble checks.
Normal:Characters who wear armor with which they are not proficient apply its armor check penalty on attack rolls and on all skill checks that involve moving, including Ride.
Special:All characters except arcanists automatically have Armor Proficiency (light) as a bonus feat. They need not select it.