Are you talking about the free daily spin received on the email? Does it mean wagering on dice and events' results increase the number of free wheel spins users receive on their email or is it another feature?
If it's another feature, where can I claim this extra free spin every day?
Freebitcoin wrote about another feature that they added to the site recently. This feature allows you to exchange RP for extra WOF spins. And as they said above, the initial daily exchange limit is only 1 spin per day, but you can increase it if you wager enough. By the way, you can find more information about it in the rewards tab.