Make a Stealth check against the Perception DCs of the creatures around you that you are not Observed by.
You take a -4 Penalty to your skill check for every size category your size exceeds Medium, and gain a +4 Bonus to your skill check for every size category your size is below Medium.
If you have Cover or Full Cover from a creature, you gain a +2 or +4 Bonus to your check, respectively. On a Success against a particular creature’s Perception DC, you become Hidden from that creature. If you were already Hidden from that creature, you retain that condition.
If you successfully become hidden to a creature but then cease to have cover or greater cover against it or be concealed from it, you become observed again. You cease being hidden if you do anything except Hide, Sneak, or Step. If you attempt to Strike a creature, the creature remains flat-footed against that attack, and you then become observed. If you do anything else, you become observed just before you act unless the GM determines otherwise. The GM might allow you to perform a particularly unobtrusive action without being noticed, possibly requiring another Stealth check.
If a creature uses Seek to make you observed by it, you must successfully Hide to become hidden from it again.