4.5 years contract: 880 teaching hours (10%).
5 years contract: 1760 teaching hours (20%).
You can publish master theses projects to get candidates here: https://annonsportal.chalmers.se/CareerServices/en/Ads/Index (discuss with your supervisor beforehand).
It may depend on your department, but usually we send an email to the director of studies of the department to report how many hours of teaching we did for each course.
You can see your teaching allocations here: chalmers.retendo.com