Nano: how to just open a new file buffer inside of nano without altering the current one?

I love the nano feature that enables you to open multiple files at once and the fact that switching between them is very easy:

nano file1 file2 etc.

However, when I try to open a new file while working on one with ^R, it just inserts the whole fine within the file I was working on after I enter it. What I want to know is how to open a separate tab with a different file. M-F just gives me an error that says "[No formatter is defined for this type of file]".