Shopp 1.2 (https://shopplugin.net) doesn’t provide a native way to show sku for the selected variant. This plugin solves that problem.
Support
If you need support, e-mail info[a]crazyxhtml.com
Hire Me
If you need a WordPress or Shopp developer, I’m available: info[a]crazyxhtml.com
This plugin is available for download for your site.