I was having some trouble authoring a Windows Performance Recorder profile by hand-editing the XML, and I wanted to check it against the schema.
This MSDN page says "you can get the WPRControlProfiles.xsd file in %ProgramFiles(x86)%\Windows Kits\8.1\Windows Performance Toolkit". That appears to no longer be true.
I dug around a little and eventually found it. It's a resource in %ProgramFiles(x86)%\Windows Kits\8.1\Windows Performance Toolkit\windowsperformancerecordercontrol.dll - the rest of the instructions seem to work fine.
You can extract it by opening the .dll in Visual Studio, expanding to the right node (highlighted above), then right-click and choose "Export".