You cannot use PDFs in our program. You need to convert them to JPEG files and then they can be uploaded as images to a recipe.
You can add a photo to a recipe when you first add the recipe. To add a photo to an existing recipe, go to any index under "View Recipes" such as "Index by Category" or "Index by Contributor" to view the list and click the recipe title to view it.
In either case on the recipe add/edit screen, you will see a button "Add Recipe Photo" - click that. That will open a screen to select a photo and upload it. Once added, the Editor can click "[Edit Photo]" to change the size, centering and border effects.