The best way that we have seen to print out 4x6 cards is in Internet Explorer.
Go to a recipe page and click on File > Print Preview.
In the Print Preview window:
1. set the page to Landscape mode
2. go into Page Setup by clicking on the settings icon on the top left
3. under "Page Size", choose Post Card 4x6"
4. under "Margins", make sure everything is 0
5. make sure all items under Headers and Footers say "-Empty" and click OK
6. in the % window at the top, choose the right percent so that the entire recipe fits on one page. I have found that this is between 32-42%. You can choose "Custom" to set the exact percentage.
7. once you have set all of those settings and you see the entire recipe on the print preview screen, click the Print icon on the top left and print out the recipe