Title: How to: Create a Custom Activity for Workflow Manager 1.0
I checked in both the C:\Program Files and C:\Program Files (86) areas and there's no Workflow Manager folderset.
Standard install of Visual Studio Professional 2012.
The tutorial (for me) fails at Step 7: "Click the Browse button and navigate to C:\Program Files\Reference Assemblies\Microsoft\Workflow Manager\1.0"