OK I got this worked out and am posting my solution here in case anyone else is interested in doing this.....keep in mind YMMV! This is just one possible solution.
One very simple solution is to add a custom field to the page on which the reviews would display, the put in that custom field the shortcode, then echo the custom field in the template. That would work if we only had a few pages on which to add the custom field, but the site I'm working on has thousands of pages.
Thus I needed to be able to use a PHP call to display the review(s) in my template, and so the the attribute (category="whatever") needed to be variable so that it can be matched to the product category, which is already stored in a custom field.
SO I added this to my template where I wanted the reviews to display:
$mycat = get_post_meta($post->ID,'product_category',true);
$myshortcode = 'RICH_REVIEWS_SHOW category="'.$mycat .'" num="3"';
$myshortcode = '[' . $myshortcode . ']';
We don't display the form on the product page (since we invite reviewers and keep the form on a private page), but you could use the same code to display the form and set the category for the form to match the product too.
I also used the same code to display the SNIPPET (aggregate reviews) on each product's parent category page.
I hope this helps someone!