According to your description, you want to add a report template by placing a custom report to the location which you post, however, the report template is not available when adding a new item for a report server project in Visual Studio. Please understand
that the location of template reports are different under different versions of operating system. If it’s a 32-bit operating system, then the location of templates will be located in the place which you give. If it’s a 64-bit operating system, then the location
is: C:\Program Files(x86)\Microsoft Visual Studio 9.0\Common7\IDE\PrivateAssemblies\ProjectItems\ReportProject.
In your scenario, please check whether the OS is 32-bit or 64-bit first, then store the custom .rdl report in the correct folder.
If this issue still exists, please provide us more information about the issue, such as post the screenshot of the details of the ReportProject folder. Then, we will make further analysis and help you out.