Show Post Thumbnails in RSS Feed

By default WordPress will only show text in your RSS feed but if you want to include your set featured image this snippet will do that.

This will add the post’s featured thumbnail before your content in your site’s RSS feed.

<?php
//This will prepend your WordPress RSS feed content with the featured image
add_filter('the_content', 'smartwp_featured_image_in_rss_feed');
function smartwp_featured_image_in_rss_feed( $content ) {
  global $post;
  if( is_feed() ) {
    if ( has_post_thumbnail( $post->ID ) ){
      $prepend = '<div>' . get_the_post_thumbnail( $post->ID, 'medium', array( 'style' => 'margin-bottom: 10px;' ) ) . '</div>';
      $content = $prepend . $content;
    }
  }
  return $content;
}