They don’t normally show there
That is how they are supposed to work.
Each CPT has a feed of it’s own by default
Everything in WP has a feed it seems!
But if you want them in your main feed
this can go in your functions.php
// ADDS POST TYPES TO RSS FEED
function myfeed_request($qv) {
if (isset($qv['feed']) && !isset($qv['post_type']))
$qv['post_type'] = array('ve_products', 'post');
return $qv;
}
add_filter('request', 'myfeed_request');
You see this line:
$qv['post_type'] = array('ve_products', 'post');
That includes normal posts and my CPT of ve_products in my main feed
You would swap out that for your CPT, if you have more CPTs, add them into that array