The propeller is not suitable for e-foil, you can’t put a quality propeller on a splined shaft. Only a very low selling price would compensate for that.
With a a hole drilled into the shaft for a pin the Fliteboard prop will fit fine (the splines have a 11mm diameter with is the same as the prop).
If you wanted to use the FR prop then all you need to do is drill a hole for a pin and then take off 5mm of the spline. This took me 10 minutes…