For 2024 Pilgrims: €50,- donation = 1 year with no ads on the forum + 90% off any 2024 Guide. More here. (Discount code sent to you by Private Message after your donation)
Go to the cathedral and ask one of the attendants, explaining what you want. They will take you to the side door where you go in to get the stamp. I've done it a couple of times
This site is run by Ivar at in Santiago de Compostela.
This site participates in the Amazon Affiliate program, designed to provide a means for Ivar to earn fees by linking to Amazon