Unfortunately, RadChart does not provide this functionality.
Alternatively, you can create an external list of CheckBox controls and
respond to their Checked/Unchecked events to Add/Remove data series.
You can customize the color of the line series using the appearance API
exposed by the series definition. Here is a sample:
|dataSeries.Definition.Appearance.Stroke = new SolidColorBrush(Colors.Blue);
Hope this will help.
the Telerik team