Add

functions.php

<?php

// What is this:
//   Feedly shows an icon on the feed for each blog. If You have a logo in your webfeed then it'll show that logo.

// Add a namespace to the root tag. This allows you to use <webfeeds> tags later
add_filter( 'rss2_ns', 'feedly' );
function feedly() {
  echo 'xmlns:webfeeds="http://webfeeds.org/rss/1.0"';
}

// Change these URLs for your logo
add_filter( 'rss2_head', 'feedly_head' );
function feedly_head() {
 echo '<webfeeds:cover image="https://cdn.minafi.com/wp-content/uploads/2017/09/03195920/mfi-logo.png" />';
 echo '<webfeeds:icon>https://cdn.minafi.com/wp-content/uploads/2017/09/03195920/mfi-logo.png</webfeeds:icon>';
 echo '<webfeeds:logo>https://cdn.minafi.com/wp-content/uploads/2017/09/03195920/mfi-logo.png</webfeeds:logo>';
}