Unfortunately I am unable to reproduce the problem.

I can without difficulties enter a tuplet of {4 16ths in the space of 3 Eighths}.

If you can explain your rhythm entry steps, then we may be able to tell what you are doing wrong.

Meanwhile, I suggest that you study Mike Rosen’s tuplet tutorial at

http://www.specialmillwork.com/finale-tips-and-tricks/ 

If you enter the tuplet as 4, 16ths in the space of 6, 16ths, you won't get the extra rests.

Apologies to Peter (I tried to reply to your e-mail, but wasn't allowed ...) and to Mike for my slow response. I had to put this music aside for a while. Mike, a strange thing just happened: I followed your idea, but there were too many notes and it wouldn't fit. However, I noticed that it looked OK after putting in 3 of the four semiquavers (16ths). The system isn't throwing errors at me (no unwanted rests and no spillage into the next bar) and it sounds fine. Yes, there are 3 notes instead of 4, but that isn't going to bother my choir and the pianist won't be listening! how odd, though, that it will take an incorrect number of notes - go figure! Very many thanks to both. You guys do such a helpful job. Annie O

Annie, would you be open to a quick Zoom? Maybe I can help you out. Send me a reply by email. My address is encoded in my signature. Just change the "at" and the "dot" to what they should be.

There's a certain logic to this. Once you get it, pretty easy. The trick for me always is to remember it for next time. For that reason, I never work in Finale without having the User Manual on one of my side monitors—just too much to remember.