On mapbox it's proportional bwn 0 - 1.0;
So if we want it centered it would be
CGPointMake(0.5, 0.5);
Use this:
- (id)initWithUIImage:(UIImage *)image anchorPoint:(CGPoint)anchorPoint
RMMarker * marker = [RMMarker initWithUIImage:[UIImage imageNamed:@"yourImage.png"] anchorPoint:CGPoint(0.5,1.0)];
If you want the bottom of the image to point to the location, I think you'd want either 1.0 or -1.0 as your Y point. I don't have a MapBox proj available right here to test it.