Paste this code into a text widget to put a qr code on each page.
<script type="text/javascript"> var url=encodeURIComponent(window.location); var qr="<img style=\"maxwidth:100%\" src=\"https://chart.googleapis.com/chart?chs=240x240&cht=qr&chl="+url+"&choe=UTF-8\"/>"; document.open(); document.write(qr); document.close(); </script>