Hi there,
RP Points can be used to strengthen your attacks and skills. You can check it, simply click at a small "flower-like" symbol at each skill in your tech-tree. You can see what kind of "Power-Up" the selected skill has.
There are these symbols you can find...
Damage Up
It will increase skill's damage by displayed amount.
_____________
Lowering Wastage
It will reduce the amount of EP, the skill needs to be casted.
______________
Cooldown Reduce
It will reduce the cooldown of the skill. Cooldown means the time when the skill is ready after usage again.
______________
Break through
It will break through opponent's guard. Works only at PvP.
______________
Knock down
It will knock the enemy down.
______________
Extension
It will extend the skill duration.
______________
There is the option "Manual" and "Automatic", if you choose "Manual" you have to choose its power up via pop up menu after pressing the skill's button. If you choose "Automatic", you have to mark your prefered power up first. If you want to use that skill with RP, you may simply hold pressing it for a short time to use your marked power up at last.
PS.:
I couldn't remember if was "Automatic" but i guess you will know what i mean, cause there are only two options.
I hope this will help a bit
Greetings
BBQ