vibrationdata provides a Modal FRF analysis, which assumes you have the force time history of the input location and the acceleration response at the output location, in the correct format.

kcao mentioned the "RESP" function, which computes the shock response spectrum. This can also be computed by vibrationdata, but is not a FRF.

Please attach a zip file of your data and your Workbench Project Archive so I can look at it.