In order to redeem the code you must go into the Purchase RP section of the Riot store and click the option for Prepaid Cards & Riot Pin instead of Codes in order to redeem your RP

And also $100 riot point package is the best deal because it basically gives you 2000 free RP points with purchase

A lousy 75 bucks for way more RP than you actually bargained for

Code works, provides 15000 RP

Well, my RP is gone