RichTextEdit controls
The RightMargin property specifies the size in inches of the right margin on the printed page.
To set the right margin:
Enter the desired size in inches in the Right Margin field of the Document tab page of the RichTextEdit control’s property page.
The RightMargin property takes a long value.
The following line sets the right margin of a RichTextEdit to 1 inch.
rte_1.RightMargin = 1