If you add a link element to your HTML with the appropriate rel and type attributes, any browsers and extensions that notify your website's readers when an RSS feed is available will be able to find them!
<link rel="alternate" type="application/rss+xml"
href="/feed.xml" title="RSS Feed">
(href="" should be a link to your feed, for clarity. If your rss feed isn't located at /feed.xml, you'll need to change the link.)
Other types of feeds can use this as well, just with a different thing in the type attribute (type="application/atom+xml" for atom feeds, for instance)