If you try to do that by modifying the "Footnote Reference" Style, you'll end up with 9pt superscript in the document body as well.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

Exactly.

Font size in body is 10pt so footnote reference is 10pt superscript in body (which is fine)
Footnote text is 9pt so footnote reference in footnote is 9pt superscript, but I need it to be 10pt superscript (therefore not following the standard rules).
I can't change styles, so a manual change is required which I want to automate.

I will code tonight but I wonder I better use a regex or is an easier way to get to the "Footnote Reference" (is it a field, a bookmark, a style, ?)
a) parse footnotes one by one;
b) range/select the "Footnote Reference" OR regex on footnote paragraph text ?
c) change font size to 10pt superscript

Cheers

Which is precisely the situation where a change in the Style definition is all you need...

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]