How is the RMD calculated for an IRA annuity with a Lifetime Income Rider?

My IRA annuity has a Flexible Lifetime Income Rider whereby I get 5% of the protected payment base for life. The contract allowed me to start taking this at age 59.5 and I have been receiving a 1099-R each year. I turn 70.5 in 2020 and the insurance company told me the RMD will be based on the contract value on Dec. 31, 2019. I have NOT and don't plan to annuitize this.

The contract value fluctuates and it gets reduced by the the rider payments.

What happens when the contract value goes to zero and I'm still receiving the distribution from this rider? Since the contract value is zero, there wouldn't be any RMD's. I know that I can now use the rider distribution to cover the RMD's from this IRA and my other IRA's.

I assume that I will continue to get a 1099-R for my lifetime - even when the contract value is zero. If this is correct, can I use this ongoing distribution to cover the RMD's on my other IRA's?

Also, shouldn't the RMD take into account the fair market value of the lifetime income rider? If so, the contract may be zero, however, there will always be a RMD.