UCMA RTF Formatting

I am building a chat bot but am hoping to format text with bold, etc... based on the response...

The generic bot page: http://msdn.microsoft.com/en-us/library/office/dn454839(v=office.15).aspx mentions this, but that code for enclosing text in RtfBold does not work in Visual studio 2012 saying it is not a valid method.

string text = "This "+"text".EncloseRtfBold() + " is in bold";
Reply reply = new Reply();
reply.AddRtfMessage(text);

Is there an assembly required to use this method?

Thanks,
Paul