widget snippet

hi, i want to add a widget snippet to my enfold theme?

“This is your widget snippet. Copy-paste it into the code of the pages you want to chat on. Right before the </head> tag is the best option.”

<!-- Chatra {literal} -->
<script>
    ChatraID = 'RRRXdJSx7rcmqw';
    (function(d, w, c) {
        var n = d.getElementsByTagName('script')[0],
            s = d.createElement('script');
        w[c] = w[c] || function() {
            (w[c].q = w[c].q || []).push(arguments);
        };
        s.async = true;
        s.src = (d.location.protocol === 'https:' ? 'https:': 'http:')
            + '//call.chatra.io/chatra.js';
        n.parentNode.insertBefore(s, n);
    })(document, window, 'Chatra');
</script>
<!-- /Chatra {/literal} -->

Where an how can i add this snippet into the site? i use an enfold child theme. can i add this to the footer.php (child)?? to which position in the code?

thank you very much.