We test whether radial dark matter fraction profiles f_DM(R) within individual galaxies exhibit a staircase morphology—discrete plateaus at (N-1)/N connected by sharp transitions—as predicted by the phase space dimensionality framework (Radial Dimensionality Theory). Using the full radial rotation curve profiles of 76 quality-selected SPARC galaxies (1,830 data points), we apply five statistical tests comparing piecewise-constant models against smooth null models (NFW, pseudo-isothermal, and model-agnostic splines). Result: The staircase prediction is not supported. Only 7.9% of galaxies prefer piecewise-constant fits (threshold: >25%), with 0% among massive spirals—the best targets. Apparent signals in dwell time and residual structure are artifacts of asymptotic curve flattening, not staircase structure. Results are robust across 13 analysis variations. The non-discriminating predictions (monotonically increasing f_DM with correct mass ordering) are confirmed but shared with ΛCDM. Combined with the Paper I global null result, this establishes that the f_DM = (N-1)/N quantization prediction does not produce detectable discrete structure in SPARC rotation curve data.