FYI... After creating a custom content type called "Frequently Asked Question", I then clicked on "Comment Display" tab and it displayed these errors. Note: I haven't added any formatter_reference fields to this content type.

Notice: Undefined index: settings in formatter_reference_form_field_ui_display_overview_form_alter() (line 313 of /home/quickstart/websites/profile.dev/profiles/da7/modules/contrib/formatter_reference/formatter_reference.module).

Warning: Invalid argument supplied for foreach() in formatter_reference_form_field_ui_display_overview_form_alter() (line 313 of /home/quickstart/websites/profile.dev/profiles/da7/modules/contrib/formatter_reference/formatter_reference.module).

Hope that helps