Add code provided by addthis support

Hi guys

I recently faced an issue with addthis sharing buttons not showing in some pages. When I contacted their support they gave me this code and told me to add it to the footer.php file. Can I add it to the footer styles under design setup, and how would I add it there? The code is

[code title=””]<script data-cfasync=”false” type=”text/javascript” src=”//s7.addthis.com/js/300/addthis_widget.js#pubid=yourkey” async=”async”></script>[/code]