No you don't need to calculate it and do all that. It's whatever they send you. Say all of it is the RMD. If you have a RMD requirement it will ask you if it is the RMD. Say yes and enter the amount as the RMD amount. The pension doesn't need to calculate any RMD. Anything your pension pays you is considered to be the RMD. Traditional pensions automatically fulfill the rules of an RMD. So just enter the same amount in box 1 for the RMD for each 1099R.
