Use the SelButtlet method to display Bullets and use the BulletIndent property to determine how much you want to indent after each Bullet.
Code:
'Set the bullet Indent to 25.
RichTextBox1.BulletIndent = 25
'If the Bulleting is OFF, turn it ON, if it's ON, then turn it OFF.
RichTextBox1.SelBullet = Not RichTextBox1.SelBullet