If placement learning makes up 25% or more of a course, either in terms of time (e.g. one year out of four) or in terms of credit (e.g. 45 credits or more on a 180-credit Masters degree) then formal approval is required. If it is a new course you will need to fill in Part 3 of the Course Approval form and submit it along with all the other required parts of course approval paperwork. If you are introducing placement learning to an existing course you will need to submit Part 3 of the Course Approval form - and as this is likely to be a major or significant revision of the existing course, you are likely to need to submit a new Part 1 Course Approval form as well.
The Course and Module Approval pages have more information and the forms to fill in.