So, for posterity:

  1. Everywhere on the net says to put the below in your csproj file:

    <PropertyGroup> <TargetPlatformVersion>8.0</TargetPlatformVersion>< /PropertyGroup>

This is actually incorrect if you are running windows 8.1, you have to put 8.1 there instead of 8.0. This change will allow you to reference the "Windows" assembly in the windows -> core section of the references dialog. Putting 8.0 there gets you a bunch of other things there that you don't want.

  1. you also have to reference this dll:

C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETCore\v4.5.1\System.Runtime.WindowsRuntime.dll