Adding something at end of each WordPress post

<?php
function add_like_dislike($content) {
        if(!is_feed()) {
                $content.= '<div class="likedislike">';
                $content.= '<button>Like | Dislike</button>';
                $content.= '</div>';
        }
        return $content;
}
add_filter ('the_content', 'add_like_dislike');
?>