There is a C++ entry for QueryProjectionTransformation in the RealSense SDK documentation (at least, the documentation for the previous '2016 R2' version of the SDK). Though you are correct to suggest that having an instruction in the documentation is not an absolute guarantee that it is actually currently implemented in the SDK.
Some features that were in the R2 SDK were removed from the latest R3 SDK, including all support for the R200 camera. If you are using an R200 camera and have installed the '2016 R3' SDK, you should please uninstall R3 and install R2 instead.
If you need to install R2, you can do so with the following link that starts the download automatically.