Flex Feature Using Varying Radius

I'm trying to warp a solid rectangular geometry to follow an involute curve. I can create the involute curve easily enough using the equation driven curve generator but I don't know how to conform the rectangular geometry to it.  The closest I can get is using the flex feature tool, however this only works for a constant radius as far as I can tell.  Is there  a way to make the flex feature work for varying radius or another tool I should be using that can accomplish this?

Thanks

SolidworksParts And Features