Modelling Time Delays in a frequency domain control System

I am designing a control system in the frequency domain but now I have to model a variable time delay. I am currently using the "Variable Time Delay" block. However I am wondering if this is the correct approach since all the quantities in the system are in the frequency domain. The simulink model is given below

And this is the subsystem named "ProServo System"

Thanks in advance, Nikos