My Bigfoot-js implementation on Squarespace.

squarespacebigfootfooterinjection

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script type="text/javascript" src="/s/bigfootmin.js"></script>
<link rel="stylesheet" type="text/css" href="/s/bigfoot-number-dwpd.css">
<script type="text/javascript">
  $.bigfoot({
    positionContent: true, // required for numbered footnotes
    numberResetSelector: 'article', // restarts the numbering for each article on SQ
    actionOriginalFN: 'ignore' // show the original list of footnotes
  });
</script>

1. Download Bigfoot.js
2. Upload .js and .css to the site (Add Page → Link → Click to add URL → Files → New File)
3. Copy code into Footer under Code Injection
4. ???
5. Profitt!