Google Analytics Calculated Metrics are available via the GA Core Reporting API, but I cannot find it in Supermetrics side bar dropdown, nor can I find any support article for this. Will you confirm if calculated metrics are available via Supermetrics? Thanks!
Another user asked about this and I put in a request already to see if we can add the custom calculated fields to the side bar. Until then, you can add them manually through the SupermetricsQueries sheet (which may be hidden).
Here's an example of how I was able to do this:
Found the entry for my query in the SupermetricsQuery sheet and added the external name to the Metrics column, in quotes, comma separated from the other metric:
Then refreshed the query to get the metric results: