While SKULabs allows you to retrieve and view rates within SKULabs, it does not directly provide rates to your ecommerce software for checkout purposes.
Note: It is NOT recommended to allow selection of specific carriers and services that limit your options to ship in case of events like carrier API outages.
Instead, it is recommended to offer customers simpler shipping options such as free, tiered, or flat-rate shipping at checkout. This helps maximize your ability to fulfill orders flexibly with various shipping service alternatives and increase sales by reducing the amount of indecision possible during checkout.