matchHeight issue in Responsive Sheffield Blue

[swguy]

I saw there were some comments on the main support thread for this template on this topic, but I'm not sure there is consensus around the best solution. What I see as the symptom is the error message "$(...).matchHeight is not a function, as shown in the image msg.jpg below.

This arises from

<script  type="text/javascript">
  $(function() {
      $('.grids').matchHeight();
    });
</script>

However, when I comment out the call to matchHeight, I get a gray box next to the quantity box on the product info page, as shown in product_info.png below.

Any thoughts on the best way to fix this?