All retirement accounts, even pensions and annuities, must meet the RMD requirements.
However, the way the pension plans meet the RMD requirements is by creating an annuity paid periodically (in your case monthly). Therefore, you may simply select "yes" to the RMD question (Was this withdrawal RMD and all of this was RMD).
You will also be asked if the amount reported is paid periodically in equal amounts. By selecting "yes" the RMD requirements are met and you may continue with the tax preparation.
Here's more info in RMD FAQ's.