If you are a designated signer for the actual deeded owner(s) of the property, then you will need to have Power of Attorney (POA) and provide any supporting documentation that designates you as such. You will need to identify the deeded owner(s) of the property, provide your name as the authorized signer (you cannot sign as a company). Due to the nature of listing homes that are under POA, the MLS associations are very scrupulous when they see a property listed. Rest assured, they do allow them, but if they find inaccurate information, they will most likely cancel the listing and levy a fine. So be sure to provide accurate and complete information.