Dropbox sync - where are the .dtSyncStore folders

I have managed to sync one database successfully with Dropbox, fortunately ignoring the instructions to exclude the Apps folder. But where are the .dtSyncStore folders that I am supposed to uncheck in Dropbox/Preferences/Advanced/Selective Sync? I have yet to find one there, or in my Dropbox/Apps/Devonthink folder on the Mac or on the Dropbox website.

My situation exactly. Any thoughts? Just curious.