Add button to Related Item

I am using CRP, it’s working great!
Now, I would like to, for each Related Item, add a button to allow users to save the post to their “Favorites”.
I am using this plugin:
https://favoriteposts.com/

Which requires that I add the following function:
the_favorites_button($post_id, $site_id);

where $post_id is the postID of the related item, and $site_id defaults to my site ID.

Where could I add this to the array of CR Posts?