The font size, in half-points
property FontSizeDouble: Integer;
The default value of this property is 0. This means the item uses the default font size defined in TRVMathDocObject item of DocObjects collection.
This value is measured in half-points, i.e. FontSizeDouble = 20 means 10pt, FontSizeDouble=21 means 10.5pt.
Use TRichViewEdit.SetCurrentItemExtraIntPropertyEx to change value of this property as an editing operation (rveipcFontSizeDouble).