Better Way of Manipulating RichText in C#?

RichTextBox rtb = new RichTextBox();
Font boldfont = new Font("Times New Roman", 10, FontStyle.Bold);
rtb.Text = "sometext";
rtb.SelectAll()
rtb.SelectionFont = boldfont;
rtb.SelectionIndent = 12;

public static void Set(this RichTextBox rtb, Font font, string text)
		{

        	rtb.Text = text;
			rtb.SelectAll();
        	rtb.SelectionFont = font;
            	rtb.SelectionIndent = 12;
                 return rtb;

		}

someRtb.Set(yourFont, "The Text").AndThenYouCanAddMoreAndCHainThem();