Here are a few options, all of which will insert the PTC in-line (series) with the Hot power connection feeding into the coil:
1) In this example, the enamel coil wire would be de-soldered from the switch return wire terminal and one of the PTC leads wired in its place. The other leg of the PTC would be soldered to the freed coil wire and shrink wrapped.
2) alternatively, the PTC could be wired as below into the switch send OR return wire
A 3rd option, not shown, would be if using a terminal strip to distribute power to the Uncoupler, the PTC could be wired from there in series with the Hot wire going to the Uncoupler.
Also note that the above pictures show the locations for the Activation button connections when using Track power. If providing Aux power and Aux ground to the Uncoupler, the connections would be as follows (PTC not shown).
