The Capabilities selection should be part of the Application Package wizard "Create New Package". In 831 it is only available if you open an existing package.
The scenario is an application that has an internal manifest with RequireAdministrator. Currently, you must package and save the package, and then reopen it just to set the capability for RunAsAdministrator.
If the capability is not set the launch fails as the runtime is blocking it. Although oddly you can right click on the shortcut to the app and use more-->RunAsAdministrator.
