Did you know that if you create a custom post type, it will not automatically be included in your site’s main RSS feed? That is because this feed is technically just a feed for posts that have the post_type post, which is fine for most sites since all posts are ‘posts’. (Try and make a sentence with more legitimate uses of the word post…).
However, if you start developing your site a little more and end up creating a custom post type, you’ll soon realise that your readers aren’t getting that information unless you intervene.
Fortunately, it’s a quick fix and it just requires a little snippet with very little customisation. Drop the following snippet into your functionality plugin and then add the custom post types to the array in line 5 as appropriate. You can add as many or as few as you want. In this example, I’ve added custom post types called gallery and product (note that you must leave post in there if you want to keep your posts in the RSS feed):