We don't key signatures of witnesses from the last page of testimony. (I assume we don't key claimants either.) However, will this last page be obvious to us that that's what is it? I don't recall seeing an example of this.
I don't think that I've run across such a page. Hopefully it will have questions (looks like testimony) with witness signatures at the end and actually look like the end of something.
Of course I know new testimony can begin on the last page, too......!