Sets or returns the proportional font size setting in the host application, in points. Read/write Single.
Remarks
When you set the ProportionalFontSize property, the host application does not check the value for validity. If you enter an invalid value, such as a nonnumber, the host application sets the size to 0 points. You can enter half-point sizes; if you enter other fractional point sizes, they are rounded up or down to the nearest half-point.