First page:

{{#tag:ref|Footnote text before overflow.<includeonly>{{#section:Page:[Second page]|overflow}}</includeonly>}}

Subsequent pages:

<section begin=text/>Page text<section end=text/>

<div style="font-size:smaller;">
<section begin=overflow/>Footnote overflow.<section end=overflow/>
</div>

Transclusion:

{{Page:[First page]}}
{{Page:[Second page]|section=text}}