I wrote some time about about making 10m contours with KP.https://www.facebook.com/groups/485564718218028/pe...
Same methods apply to 5m, It depends what you actually want, "raw" 5m, smoothed 5m without interpretation or smoothed 5 with interpretation or what.
If you try to do a bit more generalized map (for scale 1:25 000 or something) making normal 5m + form lines and dropping out all form lines isn't good way to do it, plenty of details would be lost. It would be better to scale z values in advance with 0.5 factor and make normal KP 2.5m contours, those would then be 5m contours.
additinal raw 5m contors can be done by setting "basemapinterval" parameter 5 in kp ini file.