Most of potassium rich foods that I can think of have carbs.
100g of spinach contains 558mg of potassium and 1.4 net carbs. 500g would be 2790mg potassium and 7g net carbs which seems like plenty of potassium for few carbs. Broccoli, mushrooms, avocado, Greek yogurt, seafood, nuts and seeds are also good sources and suitable for a keto diet.
I supplement with potassium and sodium on the keto diet… so yes but through my supplementation.
Just FYI RDA for electrolytes really doesn’t mean anything.
On keto and especially if you fast and do keto your sodium and potassium demands are going to be a lot higher than normal, hence why supplementation is recommended.