Adjuvant is when radiation is done as part of the first treatment plan alongside surgery. Salvage radiation is done when there is a future biochemical recurrence with a rise in PSA after surgery.
I too had a positive apical margin. In my case the Dr did not recomment adjuvant radiation. My PSA was 6 and I had a microscopic margin.
Whether to start radiation immediately (adjuvant) or wait for a rise in PSA (salvage) is a tough decision. I wish you all the best.