Your WebRender deployment URL can be found in the dashboard
PageSpeed Insights provides a really good toolset to analyze how well WebRender is working for your domain. Input your current domain without WebRender, and then input your WebRender deployment URL to see the difference.
One of our favorite ways to test is by simply curling your WR deployment URL with the user agent you're trying to test for.
Look for the last text before the end of the
</body> to see the cache status of your page. You will also see a
WRCacheHit header returned as
1 if the cache was hit.