Hi,
Are you Java Machine Agent or .Net Extension Manager to reoport Custom Metric ?
In case of Java Machine Agent using https://docs.appdynamics.com/display/PRO43/Build+a+Monitoring+Extension+Using+Scripts
Then we just to make sure the output to std out is in format
name=<metric name>,value=<long value>,aggregator=<aggregator type>, time-rollup=<time-rollup strategy>, cluster-rollup=<cluster-rollup strategy>
you can just use PowerShell's write-host to send it to std out
In case you are using .Net Extension Manager you can use following extension
https://www.appdynamics.com/community/exchange/windows-script-monitor/
write-host "metric1 | instance1 , value = $Value";
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