join depending on the "randomized number," for example, if the randomized < 20, then join

case when (ISNULL(rnd_c03.RANDOM_NUMBER,99) BETWEEN 0 AND 20) then LEFT JOIN [rtdm_main].[RTDM_SCORE] C03
ON res.RUN_ID = C03.RUN_ID AND sdms.SCORECARD_TYPE = 'C03'

Thanks for the answer!