How to add a custom button to Easy Property Listings

<?php
function my_epl_custom_email_friend_button_callback() { ?>
    <div class="epl-button button-email-friend">
        <a class="" href="mailto:?subject=<?php the_title(); ?>&body=Hi, this email has been sent to by your friend from <?php the_permalink() ?>">Email a Friend</a>
    </div>
<?php 
}
add_action('epl_buttons_single_property', 'my_epl_custom_email_friend_button_callback');
?>