size Property
Sets or returns a String that represents either the size of the font (when applied to the FONT element) or the height of a horizontal line (when applied to the HR element).
expression.
expression Required. An expression that returns one of the objects in the Applies To list.
Example
The following example inserts a horizontal line at the beginning of the active document and sets the height of the line.
Dim objLine As FPHTMLHRElement
ActiveDocument.body.insertAdjacentHTML "afterbegin", "<HR>"
Set objLine = ActiveDocument.all.tags("hr").Item(0)
objLine.Size = "5"