Your proof must convince a reasonable person the claims in your title are true. Mods reserve the right to pull any AMA and ask for more proof so please be as thorough as possible.
a) For tangible public proof that you have photographed, we strongly recommend you include a small sign, handwritten, with your username and the date. Uploading it with Truepic is even better.
b) Digital public proof must come from a verified social media account or be verified as an official social account on your company or organization's official page. The best digital proof originates on your official webpage. This should also include your username, mention that you are doing an AMA, and the date of the AMA.
Some examples of good public proof include:
Adding a note to a website or twitter feed that only the real person or organization would have control over.
If you are going to use your official Social Media site, please include the username you will be using and/or link to the AMA once you have posted it. This will ensure that no one can pose as you!
A photo of you with a sign that says "Reddit" or your username, or something like that. However, this only works if there are other publicly available photos of you to compare it to. Something identifying like a work ID, a business card or documents like a pay stub or contract, with confidential identifying information blocked out.