The Bezier chart in RadChart is actually a cubic Bezier curve (you can find more information here
) - that is you need at least 4 points to draw a curve - the first and the fourth points would represent the curve's ends, while the inner points will be the control points and they will not necessarily lie on the curve. That said, if you need to add more points you need to add at least 3 of them. Now the next part of the curve is defined by points #4 to #7, where point #4 and point #7 define the start and the end of the curve segment and points #5 and #6 are the control points. So generally you need 1 + 3xN (that is 4, 7, 10, 13 etc) points to define the chart.
the Telerik team