Virtually all pension plans/annuities are a type of financial mechanism that requires RMD's after reaching the age of 70 1/2, even though you have no control over that - or do not even realize that it is a RMD. In effect, all qualified annuities are RMD's.
When you are receiving a regular monthly payment from a pension plan, or a regular distribution from a retirement account or annuity, it usually has been "amortized" over your expected lifetime, or over some "period-certain" of 10+ years. This is exactly what the RMD is all about. The IRS wants to be sure you are receiving (and paying tax on) adequate distributions from your retirement accounts each year.
So, if you are continuing to receive the same pension/annuity/retirement account distribution every month/year over your expected lifetime, then you are indeed receiving your RMD each year. You are not in jeopardy of having failed to receive your required annual RMD each year. It is automatic. As long as you are receiving periodic payments, you have met the RMD requirement.
The second question on the TurboTax form is "How much of...(the amount you receive) applies to the RMD which needs to b taken out?"
Choices offered are: ALL or PART......... How do we know??
If you are receiving a pension payment, then ALL of the pension payment applies to the RMD (see ChristinaR's explanation, above).
If you are taking a distribution from an IRA or 401K, some or all of that distribution may constitute a Required Minimum Distribution.
Go to this website for information on How to Calculate Required Minimum Distribution (RMD).
After determining what your RMD is for a given tax year, you can make the required withdrawals. In the case of having multiple retirement accounts, you will have to decide whether to take the entire RMD from one account, or to take partial distributions from several accounts.
If you take more than is needed from any one account (to meet the RMD), then you would indicate that only part of that distribution was for your RMD.