WaterMark
I make lots of stationery.
I have it on my site for anyone to download.
So, I thought I would show you how to make a simple
watermark to mark your Stationery.
You could put your web-site address
or whatever you want to show you made the stationery.
Open a new Image 300x300.
Add the text you want in the font you want to use.

On the layer palette,
Right click to get this menu.
Click on Delete.
This will remove all but the
marquee. (marching ants)

As shown.

Image,
Drop Shadow.
Here are the settings I used.

OK.
Now select none.
You can click on the select none Icon as shown,
or Selections, select none.

Crop the unnecessary space.

Save as a tube.

Open your stationery. Add a layer.
Re-size your watermark as needed to fit your stationery.

As shown

I place it in a inconspicuous
place.
and where it can't be cloned over. :)

To make the watermark darker,
duplicate the layer.

I've shown it here as a background.