I don’t know what the rules are in North America for roundabouts but in Europe, you’re supposed to signal once you’re on the roundabout to inform people that are coming to the roundabout whether you’re exiting or staying on.
Usually, for large roundabouts, if you enter and need to exit 1/4 through, you put your right signal on right away to let any car coming in at 1/4 know that you’re exiting and they can come on.
If you’re going 1/2 through (i.e. straight through) you put your right turn signal after the 1/4 street.
If you’re going 3/4 through, you put your left turn signal to indicate you’re staying on the roundabout (i.e. cars, don’t come in the roundabout yet as I’m staying on) and then switch to the right signal after you pass the 1/2 mark (as you’re now getting ready to exit at the 3/4 mark).
In small roundabouts though, most people don’t signal if they’re going straight through (1/2 exit) as that is the expectation (since it’s a small roundabout) but if it’s a small roundabout and you’re not going straight through (i.e. you’re exiting at 1/4 or 3/4), you should put your signal on (right for 1/4; left and then right for 3/4).
At least that’s the accepted norm for Western Europe like France, Belgium and Switzerland.
I do the same thing in Ontario for the 5 or so roundabouts I’ve been on in this province and people seem to understand what it means.