How to supply proof that you are a reviewer for a journal? How can you prove that you are a reviewer for a certain journal. For example, I have been invited to review a paper in a certain journal and on my CV I want to write that I have reviewed in this journal but since reviewers are supposed to be anonymous, how can I supply proof that I have reviewed in this journal?
You don't need to prove it. If someone thinks you're lying, they can just contact the journal editor and check. Reviewers aren't supposed be completely anonymous, anyway. It's just that no one outside of the editors should know who reviewed which articles.