In México, an RFC is used by individuals and corporations for tax purposes. It's similar to a TAX ID and/or an EIN Employer Identification Number.
Residents of Mexico are REQUIRED to have one from the age of 18 and up, even if they don't perform activities for profit.
In order to make deductions in México, a legal digital receipt called FACTURA or CFDI is required. This receipt must contain your information including your RFC.
You are ready to purchase a property? Best to have an RFC so that you can request a FACTURA for your investment, otherwise in the event that you sell, capital gains will be paid on the full amount. (Unless you have a factura to deduct your original purchase).
How do you get one?
You need an appointment with your local SAT office, you must attend in person and only you will be able to go into the office.
You will be required to bring, passport, residency card, proof of address, curp, pre-registrarion form, original and copies.
The people at www.mexprofessionals.com can do everything except show to the appointment for you.
Best of luck on your new endeavor!