If you want to add RSS auto-discovery to your WordPress site, you could manually add the link tags to your theme’s header.php file in-between the opening <head> and closing </head> tags:

<link
  rel="alternate"
  type="application/rss+xml"
  title="<?php bloginfo( 'name' ) ?> &raquo; Feed"
  href="<?php bloginfo( 'rss2_url' ) ?>"
/>
<link
  rel="alternate"
  type="application/rss+xml"
  title="<?php bloginfo( 'name' ) ?> &raquo; Comments Feed"
  href="<?php bloginfo( 'comments_rss2_url' ) ?>"
/>

Or if you can’t edit header.php, you could add a hook to your functions.php file which achieves the same effect:

add_action( 'wp_head', function () {
  ?>
  <link
    rel="alternate"
    type="application/rss+xml"
    title="<?php bloginfo( 'name' ) ?> &raquo; Feed"
    href="<?php bloginfo( 'rss2_url' ) ?>"
  />
  <link
    rel="alternate"
    type="application/rss+xml"
    title="<?php bloginfo( 'name' ) ?> &raquo; Comments Feed"
    href="<?php bloginfo( 'comments_rss2_url' ) ?>"
  />
  <?php
} );

However, there’s an even easier way. Instead constructing the link tags manually, all you need to do is add one line of code to your theme’s functions.php file:

add_theme_support( 'automatic-feed-links' );

This will automatically construct & inject the link tags into your theme’s head. Perfect!