There is no simplified method for use by an employee on the T777. The per KM rates are if you are an employer and you wish to give an allowance to your employees. Employees must use their actual expenses paid, backed with receipts.
This link is a PDF of the actual T777 form, for your reference: https://www.canada.ca/content/dam/cra-arc/formspubs/pbg/t777/t777-18e.pdf
