Go to the original FS post. On the right side of the seller's post there should be a box saying " Leave feedback for ....." Click on it and go from there.
hillsidekim wrote:
AFAIK you also have to have posted in the thread to see the box.
Kim
You are correct. I have sold some items where the buyer did not post in the thread. I always suggest they do so and allow some time for them to post prior to marking the item sold which closes the thread.