The best ways to find long term rentals in Point Roberts is to contact local real estate offices. There is no central list of rentals. Many rentals are listed in the Classified section of the All Point Bulletin.
Point Interface is sometimes used to announce rentals or to request rentals - this is an email list that sends local information about events, items for free or for sale and community announcements.
There are also listings on the bulletin board at the International Marketplace and Craig's List online.