In a 3-qt. slow cooker, mix ketchup, brown sugar, vinegar, seasoned salt and, if desired, liquid smoke. Add ribs; turn to coat. Cook, covered, on low 5-6 hours or until meat is tender.
Remove pork to a serving plate. Skim fat from cooking liquid. If desired, transfer to a small saucepan to thicken; bring to a boil and cook 12-15 minutes or until sauce is reduced to 1-1/2 cups. Serve with ribs. To make ahead: In a large airtight container, combine ketchup, brown sugar, vinegar, seasoned salt and, if desired, liquid smoke. Add pork; cover and freeze. To use, place container in refrigerator 48 hours or until ribs are completely thawed. Cook as directed.