There are two options how to create a rating, both are equivalent:
Here you can setup new rating, edit or delete it and have a overview of all ratings in your project and number of rated references.
You can easily setup new rating in this editor. Three basic options (Accepted, Postponed, Rejected) are prefilled, but can be changed. Only one Level 1 option can be chosen when rating the references. Zero or more Level 2 options can be chosen.
After saving the rating is ready to use with your references - it is displayed in the reference detail (under the Ratings tab) like this: