The house has such paneling and I have some leftover that will be used now. It has two grooves on the back. The paneling needs to be supplemented and B-max etc. have such, but according to the picture, it is not grooved. The question is: are the grooves necessary and what function do they have? If they are for twisting, the old paneling at least has warped a bit but it should go back when you screw them in, right?
The idea is probably that the grooves should prevent warping, but I also had to mix grooved and non-grooved, and all have warped equally (the fascia boards in this case). It probably doesn't help much if the wood is bad. The old fascia boards we removed were perfectly straight after 60 years, but bad in other ways.