In order to print postscript files from KFormula, you need to get the esstix fonts. These fonts can be obtained from ftp://ftp.elsevier.nl/pub/styles/esstix/esstix.zip
After downloading the fonts, install them into a folder called esstix. You can unpack them with the KDE application Ark. Right click on esstix.zip and select Extract here.... Then start the KDE font installer by going to the K menu and selecting the command Control Center->System-> Font Installer You should get the following screen:
You will need to run the font installer with root privileges. Click on the button Administrator Mode and enter your root password. Click on the button Change Folder. This should bring up a pane from where you can select the folder your fonts are stored in. In this example they are stored in /home/poincare/esstix.
Click on the the folder esstix and then click on the OK button. You should obtain the following result.
Click on the top font entry. Holding down the Shift key, click on the last esstix font, at the bottom. Your selection should look like this.
You should use the native AFM files. Set up your Settings->System as shown below. The Generate AFM's, with box should be unchecked:
Return to the Fonts tab. Click on the Install button. The fonts will install. After this you must click on the Apply button. the following splash will appear:
Answer Yes to the Apply system changes now dialog. You are done installing the esstix fonts.