To add an image to an item in an RSS feed you will need to add a new element to the item: 'itunes:image'.
Here's an example of what that looks like:
<itunes:image href="http://youwebsite.com/image.jpg" />
Make sure this element is inside the item tag in order for it to work as intended.
Wordpress automatically generates an RSS feed for you with the default settings.
We love to make use of this feature. The only downside is that WordPress doesn't automatically adds images to this feed, which can make your app look a little boring.
With this plugin, featured images from any type of page are automatically added to your RSS feed and included in the app.
The plugin is called RSS image Feed and can be found here:
Simply install and activate the plugin and you're all set!
Make sure you have your feed set up to use the images in the list like this: