Could you please let me know
What's the command line argument to use if we wanted the test suite report in pdf format?
As RAO Mentioned you can find all the command line parameters in the link provided. The only thing that may be a bit unclear is that you need to make sure that you do not specify a TestCase so that the TestSuite Report can be made available. Sample CLI:
testrunner.bat -sTestSuite -j -fC:\reportFolder "-RTestSuite Report" -FXML "-EDefault environment" C:\Users\temil.sanchez\.readyapi\loadui\agent-projects\Ready-API-Overview-project.xml