Review Content Type already comes with stars, points and percentage rating types. However, if you wish to create a new rating type, you can do so with the help of rct_rating_types filter.
For the sake of this tutorial, we will be creating a knob rating type, that will display rating using jQuery Knob plugin as shown below:
The entire code for creating knob rating type is given below:
https://gist.github.com/chetanchauhan/79891a5f1e9f9fce4ebd