New rating feature allows to turn listing comments into ratings, great thing is that validation can be enabled for comments so admin has full control over ratings, in case there are attempts for spam or fake reviews.
To enable rating on comments, go to "Oc-admin > Comments" and click on top right Settings button.
Once you are on comment settings page, click on "Enable rating on comments" and save button:
Once done, rating is enabled for users.
For theme integration, please check Sigma theme code that contains all required functions. Rating stars are supported by themes using font awesome 4.x as well as 5.x.