Set up an RNP approach in SIM with incorrect QNH set passing through transition, (aircraft subscale set 30mb higher than airport QNH).
VSD showed everything being normal and OK. Magenta vertical path projected to correct runway touch down point, the white aircraft vertical track sat perfectly over the magenta path line, and terrain display showed terrain in the correct position in relation to runway.
Aircraft position also depicted the correct height above terrain as if correct subscale was set....
The only indication of the error was the radio altimeter on the PFD.
Appears the VSD will not assist in identifying incorrect set altimeters as this incorrect information is also feed into the VSD display and the EGPWS forward looking information.