private void radButton1_Click(object sender, EventArgs e)
{
    RadDocument document = new RadDocument();
    Section section = new Section();
    document.Sections.Add(section);

    ListStyle list = new ListStyle();

    for (int levelIndex = 0; levelIndex < 9; levelIndex++)
    {
        ListLevelStyle listLevel = new ListLevelStyle();
        list.Levels.Add(listLevel);

        bool isEven = (levelIndex % 2) == 0;
        list.Levels[levelIndex].StartingIndex = 1;
        list.Levels[levelIndex].NumberingFormat = ListNumberingFormat.Decimal;
        list.Levels[levelIndex].LevelText = isEven ? "{" + levelIndex + "}." : "o";
        list.Levels[levelIndex].Indent = 48 + (levelIndex * 24);
    }

    DocumentList documentList = new DocumentList(list, document);

    for (int levelIndex = 0; levelIndex < list.Levels.Count; levelIndex++)
    {
        Paragraph paragraph = new Paragraph();
        document.Sections.First.Blocks.Add(paragraph);
        paragraph.Inlines.Add(new Span(string.Format("ListLevel: {0}", levelIndex + 1)));
        paragraph.ListId = documentList.ID;
        paragraph.ListLevel = levelIndex;
    }

    radRichTextEditor1.Document = document;

    RtfFormatProvider provider = new RtfFormatProvider();
    var rtf = provider.Export(document);
    File.WriteAllText(@"..\..\result.rtf", rtf);
}