RMD is the Required Minimum Distribution you have to take out of your IRA or 401K plans etc. each year when you reach a certain age like 72 or 73. When you entered 1099R it would have asked you if it was the RMD and how much.
What did you get a 1099R for? Even if you just get a pension it’s considered to be the RMD. Right now there is a problem with the 1099R RMD section. They are working on it.