I cannot find .tf directive in Qspice, but possibly you should achieve get what you want with either .op or .ac directive.
Here is a simple circuit as an example. For dc analysis, if you want to get V(out)/V(in) ratio, in theory, C1 becomes open circuit and V(out)/V(in) = 0.5. Therefore, you can run a dc operation point (.op) and setup a .meas to calculate V(out)/V(in). The result is given in Output Window.
For ac analysis, in this example, V1 is set to AC 1, which means V1 is a 1V ac voltage source. .ac directive sweep frequency from 1Hz to 10kHz and plot V(out) (this plot means V(out)/V1)
This allow you to get frequency response plot.
** I use a same schematic file and mask directive to switch between dc (.op) and ac (.ac) analysis in this example.
hope this give you some hints to start with.