In the next update you will have a new option in the RSS’s settings. The new option allows you to publish RSS’s posts as images or as posts. You will see images even in the RSS’s preview.
You can see in the video bellow how to publish RSS’s posts as images:
The RSS’s reader don’t support images from any RSS feed, because a lot of RSS feed don’t follow the RSS standard. If you can’t publish images from RSS, just send me the RSS’s url and i will add support for the RSS’s format.