Unfortunately this problem isn't that easy to fix.
I have 42" Skyworth TV. There is no such setting as 'panscan' 'hdmiscan' 'overscan' etc etc. This problem is because Intel incorrectly sets the aspect ratio as of Windows 8.1 by default when you first connect and there is no physical way to adjust this setting anymore.
In previous versions of the Widi APP (4.1.19.0 and lower) the aspect ratio was adjustable for this reason. Unfortunately the monkeys at Intel decided this feature might actually help people so they removed it when implementing Widi into Windows 8.1 and also gave us a huge quality downgrade which I have also discussed and confirmed in my other thread.