With a variable rocker the rocker changes over the length of the blade.
Shorttrack blades for instance are often more flat in the middle with more and more rocker towards the ends.
The change in radius should always be gradual, like the circumference of an ellipse.
On page bending. is shown how a blade with a pure circular rocker by bending
is going to track a smaller, but pure circle.
Even if the full length of the blade is touching the ice surface (inclined angle 30 degrees)
the trace would be pure circular. Every peace of the blade on the ice tracks the same trace.
This does not count for a variable rocker!
Although it is, by proportional bending, possible to make the blade touch the ice surface
over its full length. (at an inclined angle of for instance 30 degrees)
The curve of the blade touching the ice will not be a pure circle but an ellipse.
Theoretically a skate blade with a variable rocker cannot trace a friction free curve
while bended
Another view is varying the rocker to compensate for the deflection of the skate.
Keeping the rocker circular while the skate is loaded by the gravitational and
the push-off forces of the skater.
So, still housework to be done!