Post Category in RSS feed

I’d really like to just display the category of each post in my RSS feed. I’ve looked into the code and it looks like get_the_category_rss (i think that’s what it was) is being called, but for some reason the category isn’t in my feed. Can anyone give me a hand here? Or is there a plugin to do this or something? I’d actually like to customize my feed quite a bit, I’m just getting started, it seems quite tricky, and it seems like I need to make updates to internal wordpress code. Unless I can extend the rss file into my theme or something, don’t know much about how to do that, fairly new to WP.

Thanks a lot!