for the weirdest reason, i found how to do it.
when i was in the html export dialog box, i clicked on the save settings snapshot button at the bottom left.
Then i clicked on save and then clicked on ok.
At that magical moment, it automatically selects the Jpeg over the Raw.... really weird...
This was luck.
For Photo Mechanic Developers : It would be nice to have a selection box for that option in the "html export" dialog box.
Jimmy