How to measure electrical resistivity of electroless nickel plating?

Is there a standard, accurate method for measuring the electrical resistivity of an electroless nickel deposit? For clarity, I am referring to the bulk dc electrical resistivity, rho, given by:

r = rho/A

where r is the resistance per unit length and A is the cross-sectional area (for example, see https://hyperphysics.phy-astr.gsu.edu/hbase/electric/resis.html).

I expect that a four-point probe technique is required with the deposit on an electrically insulating substrate (for example, see http://www.eeel.nist.gov/812/meas.htm#resi). Does the substrate need to be insulating, or can accurate results be obtained with a conducting one with an appropriate physical model? Are there techniques other than four-point probe that yield accurate values for the resistivity?

Electrical resistivity of EN (or other coatings) is almost always determined by the "four point method". It is described by Riedel in his book, Electroless Nickel Plating ⇦[this on Amazon affil links]

While Riedel suggests using an EN foil (stripped from its substrate) for the test specimen, I believe most test have been done on coatings applied to non-conductors like ABS plastic.

The resistivity of Ni-P coatings as a function of their phosphorus content has been well documented.