set record for window / Random article

Hope this helps:

tell application "DEVONthink Pro"
	set db to database 1
	repeat
		try
			set dum to count parents of the db
			set num to random number from 1 to dum
			set mum to parent num of the db
			set chum to count mum's children
			set num to random number from 1 to chum
			set kiddo to child num of mum
			if kiddo's type is not group then exit repeat
		end try
	end repeat
	set the record of window 1 to kiddo
end tell