ScottPlot.Plot myPlot = new();

var smith = myPlot.Add.SmithChartAxis();

// translate an impedance location on the Smith chart to a 2D location on the plot
double resistance = 0.2;
double reactance = -0.5;
Coordinates location = smith.GetCoordinates(resistance, reactance);

// use that location to add traditional plot components
myPlot.Add.Marker(location, MarkerShape.FilledCircle, size: 15, Colors.Red);
var txt = myPlot.Add.Text("0.2 - j 0.5", location);
txt.LabelStyle.FontSize = 24;
txt.LabelStyle.Bold = true;
txt.LabelStyle.ForeColor = Colors.Red;

myPlot.SavePng("demo.png", 400, 300);