Combine cereals, nuts and pretzels in a slow cooker. Mix together butter, sauce and salts; gently stir into cereal mixture. Cover and cook on low setting for 3 to 4 hours.
Uncover and cook on low setting for an additional 30 minutes; stir occasionally. Drain on paper towel-lined baking sheets; transfer to a large bowl.
Cool. Add chocolates and raisins; toss to mix. Store in an airtight container.