Hi Taylor,

Please check whether you installed or not the module "stock_landed_costs" in your db.If you already installed the module, then please group by the products by product type "Service" because landed cost fields will be considered on a service type product. 

Then Please select all those products and export them with checking "I want to update data (import-compatible export)"  as True. Now you can add these two fields "landed_cost_ok" and assign them a value 1 or True and  field "split_method_landed_cost" and assign them your desired value for e.g "equal". 

Now save and import this file, it will fulfill your requirement. 

Hope it will work you.