What “Open Graph” Tag should I use for Featured Image

Hello, my featured image does NOT get posted to Facebook but does get posted to Twitter. I’ve been pouring over your instructions. Letting the plugin not facebook choose image hasn’t helped.

You mention “Open Graph” Tags. If I select that checkmark, should I also add a tag in the text box: Default Image URL for og:image tag: ?

What should I put in there to choose the featured image.