This example draws a dotted rectangle around the inside of the plot area in Chart1.
With Charts("chart1")
Set pa = .PlotArea
With .Shapes.AddShape(msoShapeRectangle, _
pa.InsideLeft, pa.InsideTop, _
pa.InsideWidth, pa.InsideHeight)
.Fill.Transparency = 1
.Line.DashStyle = msoLineDashDot
End With
End With