Required field for reviews

Hi – I need to require users to enter the U.S. state where they had their experience with a vendor when they submit a review. Most of the vendors who are being rated/reviewed are national service providers who partner with local representatives to serve customers across the United States. So the most common follow up question when people review these companies in facebook groups is: what state are you in?

I am not a developer and do not see any customization options for reviews in the GD core or add-ons. If there is an option for adding a custom field to a review, please let me know.

Thank you