private void CreateShowDocument() { var document = new RadDocument(); document.LayoutMode = DocumentLayoutMode.Paged; RadDocumentEditor editor = new RadDocumentEditor(document); editor.Insert("Text Before Text Inside Text After"); DocumentPosition rangeStartPosition = new DocumentPosition(document); rangeStartPosition.MoveToNextWordStart(); rangeStartPosition.MoveToNextWordStart(); DocumentPosition rangeEndPosition = new DocumentPosition(rangeStartPosition); rangeEndPosition.MoveToNextWordStart(); rangeEndPosition.MoveToCurrentWordEnd(); document.Selection.SetSelectionStart(rangeStartPosition); document.Selection.AddSelectionEnd(rangeEndPosition); editor.InsertAnnotationRange(new CustomRangeStart(), new CustomRangeEnd()); this.radRichTextBox.Document = document; UpdateTextBoxText(); }