when you load the Rollei IR400 film in your camera what value do you set the camera ISO...400???
For the sake of this discussion let's say the filter is a 4 stop filter.
Yes you can: e.g. metering 1/250 s for f=11 then the correction with your 4 F stop filter factor: 1/15S for f=11 (or 1/60S for f=5,6 when you would do a handheld shot)

But for (I.R.) landscapes you're normally using W.A. lenses so that the correction of the focus is not critical within the D.O.F. )