Lighting, Light Fixtures, Ceiling and Exhaust Fans - proper way to install outside wall lantern

I am wiring my new kitchen addition and want to add a wall light outside the french doors leading out to the deck. My question is, what type of electrical box should I use and how should I mount it so that the light will sit flush with the wall when installed. The sheathing is 1/2" OSB. I intend to side the addition with double 4" vinyl. Does the box have to be weatherproof? Should it be square with an adapter ring, or octagon? The light will not be under roof cover.

hi
some will used shallow round box if there a stud behind preventing it be be inseted deeper in the wall.
Usually octogone box are used the number for tha box in electrical term is a 54151L means a octogone box with connector built in
as for outlet there number is 1104L
make sure that you seal around the fixture to prevent water entering

pg

Try this site for many options for siding mount boxes.

http://www.aifittings.com/arliprod6.htm

Here is one example in use.

http://www.aifittings.com/whnew24.htm

:)
Thanks.......you've been a great help! The website has some attractive trim options.