The portfolio method of assessment is often used in upper levels of education.

HOD has dc create a 3 ring binder portfolio, which provides an excellent assessment tool.

The History Student Notebook your ds will create in RTR can be used as an assessment for many different areas, and as it is put in order from the start to the finish of the year, academic gains can easily be seen by paging through the binder. By completing the assigned work within its entirety in a neat, complete, and organized way, dc can receive an "A" for their work.

So, your student should see the RTR teacher's guide as his syllabus for all his coursework. He should be able to pick up the RTR manual, and use it as he would a syllabus.
That being said, subject areas such as grammar and math can easily be graded. A goal for dictation can be set at the beginning of the year, and ds can strive to achieve that goal (i.e. 1 level of dictation completed in a year). The "Written Narration Skills List" can be used as an editing rubric, though this list is something for dc to grow into, one skill at a time. Perhaps you'd have a rubric with the first "x" number of skills to be portrayed within a student's written narrations for the first quarter of school. The second "x" number of skills to be portrayed within a student's written narrations for the second quarter of school, etc. You can make this more of a complete writing rubric by using the assessment tools provided in the daily plans as starting points. For example, in the written narration box, you could assign points for...
- is 8-12 sentences in length
- includes who or what topic the reading was about
- descriptors of the important things that happened
- a strong closing sentence
The Medieval History Based Writing Lessons each have their own rubric, so that will be easy to use. You can also type 1 oral narration your ds gives each quarter (or however often you wish to). This will show growth in this area. The completed DITHOR student notebook logs growth in reading. The Science Lab Sheets along with the science noteobooking can be kept behind tabs in a 3-ring binder with plastic sleeves as a portfolio based assessment as well. Those are just a few ideas I had - hope that helps!
In Christ,
Julie