image thumbnail in RSS Feed

image thumbnail in RSS Feed

I dont have much coding knowledge. getting prob with RSS feed. I copy n pasted from somewhere this code. getting title and date.. its fine, but client needs now image thumbnail too. How to put image thumbnail. plz help me..
check below code...
<li> <p> <?php echo $item->get_date('j F Y'); ?> </p>
     <a target="_blank" href='<?php echo esc_url( $item->get_permalink() ); ?>'
     title='<?php echo 'Posted '.$item->get_date('j F Y | g:i a'); ?>'>
    <strong> <?php echo esc_html( $item->get_title() ); ?> </strong></a>
</li>
Thanks in advance....