FrontendMarker extends BlamePointTracer, which will give you all five metrics (ART, RPI, EPI,CI,SC). Use that and define the path as "App|populateResponse".
You can then monitor RPI.
If you insist on using MethodRateTracer, then what you have is fine, assuming you know what "x" and "*" are. You can use dynamic substitution for "x" and "*" by using "{classname}" (without quotes).
Take the time to read this wiki page: Custom Instrumentation with CA APM