Forms for RMD for 2024

We withdrew an IRA from one credit union to another in Jan. 2024. We didn't receive an RMD form from either place for RMD for 2024. We did take some out during 2024, but doing taxes we do not have the actual RMD amount. Can I estimate the amount (suggested by Turbo Tax of 4%)?  We didn't withdraw quite enough but now Turbo Tax says there is an update to follow.  Correct?