Hello Dr.YSG,
You can use the PointMark template and add as many custom elements as you like. Here is the original template:
Here is a modified template that places an inner RadChart instead of path:
Note, that I do not use data binding in this sample, so I set an array of double values to the property DataPoint.DataItem (for each DataPoint).
In case you use data binding, the original data you pass to the initial RadChart will be referenced through the DataItem property for each DataPoint, so you can use binding such as DataItem.InnerDataSource or something similar.
Best wishes,
Evtim
the Telerik team