In the same way as in any other performance testing. You should prepare scripts that will test API. Without DT you will have limited view about reasons of potential slowness or failures. Dynatrace will help you check what is root cause of potential problems (infrastructure, wrongly written code, wrong configuration etc). It needs some knowledge to have full information from dynatrace during performance test, but without it we never do load test. In our company LT is always packed as a product Scripts + Loadtests + Dynatrace Monitoring + Analysis. Then we are making report from both perspectives. LoadTest tool and dynatrace. In general advantages of using dynatrace in such context are really wide topic.