tf : The term \'tf\' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path
This worked for me. I added the path of TF.exe ("C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE" in my case) to system environment PATH variable (through My Computer->Properties->Advanced System Settings->Environment Variables->System Variables->Path->Edit).
You can check if "tf" is working by typing "tf" in the powershell. If you get an output something as : Microsoft (R) TF - Team Foundation Version Control Tool, Version 14.102.25619.0 Copyright (c) Microsoft Corporation. All rights reserved. ......
tf is working properly.