Theme only adds additional fields to comment form. Regular fields are coming from WordPress and woocommerce and theme doesn't change them. So, if you want to add own fields, you must customize core
As this is advanced customization, it's not part of regular support, I can point you only on file and check your code if you send me
http://rehubdocs.wpsoul.com/docs/rehub-theme/child-themes/how-to-customize-your-theme/
If the product page allows website links in review comments, you can usually add your site in the **website/URL field** or include it naturally in the comment if links are permitted. I recently added my own site this way, and it worked without making the review look overly promotional.