アノテーションは幅広くカスタマイズできます。

ScottPlot.Plot myPlot = new();

myPlot.Add.Signal(Generate.Sin());
myPlot.Add.Signal(Generate.Cos());

var anno = myPlot.Add.Annotation("Customized\nAnnotation");
anno.LabelFontSize = 32;
anno.LabelFontName = Fonts.Serif;
anno.LabelBackgroundColor = Colors.RebeccaPurple.WithAlpha(.3);
anno.LabelFontColor = Colors.RebeccaPurple;
anno.LabelBorderColor = Colors.Green;
anno.LabelBorderWidth = 3;
anno.LabelShadowColor = Colors.Transparent;
anno.OffsetY = 40;
anno.OffsetX = 20;

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