Make sure GD Rating System settings are correctly set for rich snippets usage. After that, you can use Google Structured Data Testing Tool.
GD Rating System is adding fully functional and standardized rich snippet for rating or review, and you can test all your posts to confirm that rating snippet is correct. But, there is no way to influence Google to show the snippet inside search results. There is no way to know how, why and when Google displays rich snippet and even the big websites like IMDb or Amazon very often don’t have the rich snippets displayed.