perhaps I should have specified, my example was for left-driving traffic which travels clockwise in the UK. in the US its right driving traffic traveling widdershins on roundabouts.

assuming you approach the roundabout from the south, heading north, and you're driving on the left, traffic travelling clockwise on the roundabout. the first exit (west) would be "left", the second exit (north) would be straight on, the third exit (east) would be right, and the fourth exit (south) would be essentially a u-turn

as you approach, intending to turn east (left) you signal left, if youre intending to turn west (right) you'd signal right. Once you're on the roundabout, if turning east (left) you're already signaling left so you exit left, but turning west (which was right as you approached the roundabout but is now left from your POV) as you approach your exit you signal left to exit.