Canvas has fairly extensive rubric options, which allow you to attach a rubric to a Turnitin assignment instead of using Turnitin's external rubric options. In order to do this you will need to:

1. Create a Canvas assignment: Select Assignments on your course navigation menu, then select the garnet + Assignment button on the Assignments page.
   
   
2. Set the Assignment submission type to No Submission.
   
3. Fill out all other assignment details such as due and availability dates, description, title, etc., then press the Save button at the bottom of the page.
4. Click the +Rubric button.
   
5. Either create a new rubric (press the Create Rubric button), or click Find a Rubric.
   
6. Now that you have attached your Canvas rubric to your Canvas assignment, you will need to edit the assignment settings to turn it into a Turnitin assignment. Click the Edit button at the top of the individual assignment's page, then scroll down and change the submission type to External Tool. Press the Find button and select Turnitin LTI API in the pop-up window that appears.
   
7. Scroll down to the bottom of the page and press Save & Publish.

Your Turnitin assignment with a Canvas Rubric attached is now set up. In order to use this rubric while grading you will need to grade Turnitin assignments in Speedgrader.