Hi Dennis,
here is an example with an image
https://forum.getkirby.com/t/rss-feed-with-images/1835/5?u=texnixe
Instead of the foreach loop which goes through all the site files, you can fetch a single image here instead.
The adapted code would then look like this:
Fetch the first image in the folder:
<?php if($image = $item->images()->first()): ?>
<figure>
<a href="<?php echo $image->url() ?>">
<img src="<?php echo $image->url() ?>">
</a>
</figure>
<?php endif ?>
Or, if you want to fetch an image from a coverimage
field:
<?php if($image = $item->coverimage()->toFile()): ?>
<figure>
<a href="<?php echo $image->url() ?>">
<img src="<?php echo $image->url() ?>">
</a>
</figure>
<?php endif ?>
Adapt to use your field name.