Soft Proof is found in Photoshop under "View"

The idea is to show you what your print will look like after it has been printed

using a Specific Paper in your own or some other Printer.

Provided, of course, that you have already set up Photoshop to use

Colour Management as shown in the article "How to Print for Accurate Colour"

You will be able to set up a number of different options to suit the range

of Papers or Printers you use.

You will need the Paper Specific Profiles for the Printer / Printers, and these should

be installed in the Windows Color Folder.  (See the Printing Article).

Go to "View" and then "Proof Setup" and Click on "Custom".

You will get a little Dialogue Box like the above.

Click on the Drop down Arrow to the right of the Profile Box, and select the

Paper / Printer Profile you want.

Set "Intent" and "Black Point Compensation" exactly as you  have already set 

them in Photoshop Colour Settings. (See the Printing Article).

Also select "Simulate Paper White" & "Ink Black"

Once this is all done Click on "Save". 

Give the File a Meaningful Title - Like "Eps Prem Glos 1290"

Check that this file is going to be saved in a Folder called "Proofing".

Then Click on "Save".

(The Folder "Proofing" can be found at  C: \ Program Files \ Common \Adobe \ Color))

You will be returned to the above Dialogue Box, and if you now click on the

Drop down Arrow to the right of "Custom", you should see the Title of

your newly created Proof Option.

You can repeat this process to create as many "Proof Options" as you need.

With the picture Open in Photoshop, go to "View" > "Proof Setup"

and drop down the list of available options until you come to the Tiltle of the Proof

you created which will match the Printer and Paper you are about to use.

eg "Eps Prem Glos 1290"

Once you have selected which Proof Option you want, you can turn Soft

Proofing On or Off, in "View" by clicking on "Proof Colours". 

The "Tick" mark shows it is "On".

More handily, you can switch between "On" and "Off" by

holding down "Ctrl" and pressing "Y"

Remember it will always use the Option you last selected.

You should notice the Colour and Density of the Image Changing.

This new view of it is a close approximation of what it will look like once

it is printed, using that Printer, that Paper and that Profile.

You can do your Editing with "Soft Proofing" turned on, so that you get your print to

look exactly the way you want.

But it might well look very different if you ever print it using a different Printer or Paper.

If you do want to make any adjustments to the "Proof" version before Printing it is best

to make them using an "Adjustment Layer" but do not flatten layers before Saving.