I would avoid all salt subtitutes (most are loaded with potassium).
Also check food labels at the supermarket.
Fruits and veggies high in K:
Oranges, bananas, kiwi fruit, melons, nectarines, mangoes, papayas, avocadoes, tomatoes, squash
here's a site with more info:
The following site breaks down the nutritional value of foods:
Hope this helps!
I would talk to your nephrologist about going to see a dietician. They can help you with meal planning. DaVita is a kidney website with a great recipe booklet and they list potassium in their foods. Even if you don't use the recipes it should give you ideas on what types of foods are okay to use. Like for example they use apples a lot so I imagine they are low potassium.