RMD and 1099R

This is our first year taking RMD.  We received one distribution prior to April1 , 2020 but do not have a 1099R how do I report it?   We are having difficulty receiving a different RMD and may miss the April 1 deadline.  We did not receive the form they said they sent  what do we do? How do we avoid the penalty if RMD arrives late?