Whippinboy
You are getting close with your sketch but there are still problems.
First: the potential relay doesnt' not need to be fed through the main contactor contacts. You can save these for something else.
Second: the potential relay has a coil and set of normally closed contacts and there is a common connection between them. The terminals are labled 1, 2 and 5 where 2 is the common connection between the coil and the contacts. Your diagram applies to RPCs of 5 hp or less. In this case you must connect PR terminal 2 to the generated phase, You sould connect terminal 5 to L3, then connect from terminal 1 to your start capacitor and from the start cap to L1. The internal PR wiring has the coil between termianals 5 and 2. the normally closed contacts are between terminals 1 and 2.
Third: All of the run caps and start caps should be before the thermal elements. I have built them with the start caps after the thermal elements and have operated these for many years without problems but I would never put the run caps after the thermal elements and now put all the caps before the thermal elements.
I posted a simplified drawing of a 7-1/2 hp RPC in a response to jminer99er yesterday. It is about two notes below your posting. This diagram shows a start contactor controlled by a potential relay which is necessary for anything larger than 5 hp. It shows how all the components are connected but not where the actual connections are made. Look it over and you can see the relationship of all the working parts. Please note that I put the start capacitor between L3 and the generated phase whereas you have it between L1 and the generated phase. Either method works--just realize my diagram is different.
I have 5 hp plans if you need them.