What is the best toolbox to mark text?

private Form Okno(Dictionary<long, string> listAnotaci)
       {
           Form form = new Form();
           Button button1 = new Button();
           Size velikostTlacitka = new Size(90, 30);
           button1.Size = velikostTlacitka;
           button1.DialogResult = DialogResult.OK;
           button1.Text = "OK";
           System.Drawing.Point point1 = new System.Drawing.Point(155, 130);
           button1.Location = point1;
           form.Controls.Add(button1);
           var result = String.Join(".", listAnotaci.ToArray());
           result = result.Replace(".", System.Environment.NewLine);
          RichTextBox textBox = new RichTextBox();
          textBox.ReadOnly = true;
          textBox.Text = result;
           Size velikostForm = new Size(400, 200);
           Size velikostTextBox = new Size(400, 130);
           textBox.Size = velikostTextBox;
           form.Size = velikostForm;
           form.Text = "Bylo zvoleno více anotací";
           form.Controls.Add(textBox);
           return form;
       }