Does MasterCook 14 run under Windows RT 8.1? I searched the App Store but didn't find an app.
MasterCook 14, like other software programs, require a full version of Windows and not just a limited tablet operating system. You will not be able to run normal PC software like MasterCook on Windows RT 8.1. Some tablets like the Surface Pro use the full version of Windows and can run PC software like MasterCook. With Windows RT you can only use smaller apps that you can install through the App Store. You can use the web application at MasterCook.com with your tablet though. See these articles:
Windows RT is meant for tablets that don't want to run full versions of any PC software. This is why there are special apps for some Microsoft products like Excel and Word. They are apps that have much less functionality than their full functioning counterparts that requre the full version of Windows.