Does anyone know how to obtain this reference? (Microsoft.ReportDesigner.CustomReportItemDesigner)

I'm trying to follow the example at 'http://msdn.microsoft.com/en-us/library/ms345225(v=sql.110).aspx' using VS2013, and I'm afraid I'm lost.  I've never done this before.

Where do I find the DLL that will provide the object 'Microsoft.ReportDesigner.CustomReportItemDesigner'? 

For that matter, is it even possible to implement a custom SSRS object in VS2013?  Has anyone done it yet?