For each Form 1099-R, indicate no more than the gross-distribution amount (Form 1099-R box 1) as the amount of RMD required to be distributed from that account. Presumably that will mean entering an amount less then the actual RMD for the account associated with the Form 1099-R for the smaller distribution and entering an amount larger than the RMD for that other account (but still no more than the gross amount distributed from that account) for which part of the distribution was to satisfy the RMD for the other IRA. The sum of these two entries should be the total RMD required for the two IRAs combined.
