We don't add lime at all as we have a neutral soil. You shouldn't lime at the time of planting potatoes as it can cause scab. If you have very acidic soil you can lime in the autumn or early spring.

Best to plant another row without using lime.
Then when you lift the first row in August use them first.

As MG says, lime causes scab on potatoes. When my old dad was alive he always lined his potato trenches with grass cuttings to make the soil acidic.