Line 18 is for outbound freight costs. Inbound freight is added to the cost of the purchases or are part of COGS.
Read the form instructions : https://www.irs.gov/forms-pubs/about-schedule-f-form-1040
Line 18
Don't include the cost of transportation incurred in purchasing
livestock held for resale as freight paid. Instead, add these costs
to the cost of the livestock.
