When you are in Race or Die, go to The Sponsor in the middle of the lower task bar. The Sponsor will sit right in between News and Blacklist. In here, you are going to see how many Race or Die Respect Points you currently have listed at the top. Below that will be all the available options for spending your Race or Die Respect Points.
After both of those sections will be links to a number of different quantities of Race or Die Respect Points. These Race or Die Respect Points packages will come in increments of 83, 225, 500, 1425, 2500 and 4000 Respect Points. Just press the Race or Die Respect Points package you want and you will be taken to the App Store page for that package. Then you can just buy and download the Race or Die Respect Points package, bringing it onto your iPhone desktop. Then you open it and you will have the Race or Die Respect Points placed into your account.
Race or Die is still new, but expect more free Respect Points packages to be made available soon. Keep your eye out for free Respect Points, especially those that are awarded for downloading updates for other games.