In the cited reference, Keele says mic on axis at the center of the dust dome, distance less than 0.11 cone radius. Vent measurement is in the center of the vent flush with the enclosure's outside surface.

Driver response nulls at fB, and the vent response must be added after correction for area as described.

So, Mr. Widget uses the method described by Keele, also a convenient means of determining actual box tuning....

Measuring just the driver without summing the vent may get you what you want, provided the box tuning does not change due to different driver displacements, and the mic distance to the dome is precisely replicated.