In a large bowl of cold water, soak potato slices for 20 minutes. Drain potatoes; pat dry with paper towels. Wipe bowl dry; then add oil, salt, and pepper. Add potatoes; toss gently to coat. Lightly coat air fryer basket with cooking spray. Place half of the potato slices in the basket, and cook in two batches at 375°F until cooked through and crispy, about 25 to 30 minutes. Using a pair of tongs, carefully remove chips from air fryer to plate. Sprinkle over rosemary; serve immediately or store in an airtight plastic container.