Simple and straightforward:
1) Create your recaptcha fields normally with this:
<div class="g-recaptcha" data-sitekey="YOUR_KEY_HERE"></div>
2) Load the script with this:
<script src="https://www.google.com/recaptcha/api.js?onload=CaptchaCallback&render=explicit" async defer></script>
3) Now call this to iterate over the fields and create the recaptchas:
<script type="text/javascript">
var CaptchaCallback = function() {
jQuery('.g-recaptcha').each(function(index, el) {
grecaptcha.render(el, {
'sitekey' : jQuery(el).attr('data-sitekey')
,'theme' : jQuery(el).attr('data-theme')
,'size' : jQuery(el).attr('data-size')
,'tabindex' : jQuery(el).attr('data-tabindex')
,'callback' : jQuery(el).attr('data-callback')
,'expired-callback' : jQuery(el).attr('data-expired-callback')
,'error-callback' : jQuery(el).attr('data-error-callback')
});
});
};
</script>