How do you add images to the feed for a post?

I tried using cover_image in the metadata. That applied an image to the post itself, but the image didn't appear in feeds for that image. For example, images appear like the following:

Is there something additional you need to do in order to make this happen?

Here are my guesses:
1.) Cover images need to fix certain width/height constraints to appear in the feeds
2.) Images need to be approved to appear in the feeds
3.) There's another metadata tag I need to add to posts.

Any help would be appreciated.

For additional context: Here's a screenshot of my post with the cover_image.

Here's a screenshot of my post in the feed:

Comments

[Matthew Collison]

So the way this works is, if your post is at the top of the list on the homepage
(which is slightly random) - your cover photo will be shown.

However, if you post a video (ours was a video snippet), then a thumbnail of the video is always shown. I guess this is to signify that the post is a video.

Hope that helps!

[Bob Cavezza]

Thanks! That's useful to know!