The RadiusLowerRight property returns or specifies the radius of a rectangle's lower-right corner. The radius is measured in document units and is not relative to the size of the rectangle.
Examples:
The following VBA example rounds the corners of the selected rectangle by specifying a different radius (0.1", 0.2", 0.3", and 0.4") for each corner.
Sub Test()
If ActiveShape.Type <> cdrRectangleShape Then Exit Sub
With ActiveShape.Rectangle
.RadiusLowerLeft = 0.1
.RadiusLowerRight = 0.2
.RadiusUpperLeft = 0.3
.RadiusUpperRight = 0.4
End With
End Sub