Preheat oven to 400 degrees. Line a sheet pan with parchment. In a large bowl, whisk together vinegar, oil, lemon juice and zest, and rosemary garlic rub. Toss chicken, potatoes and onion with mixture and arrange on the prepared baking sheet with the skin side of the chicken up. Bake, uncovered 45 minutes until the chicken is cooked through and potatoes are tender.