Do I have to live there? Or can I just let the lender know that I plan on this being a rental property?

Sorry Peter, this is going to be a little harsh.  If you want good answers, you have to form a good post.  This is not a quality post.  You need to provide more info.  

To take some stabs at this, yes, you can purchase a property as a rental right from the get-go. Alternatively, if you said this was going to be purchased as a primary residence, then rented it out, you won't have been the 1st person in the world to mislead a lender with regards to owner occupancy status, but this strategy has its risks.

To decide between the two options, the following things matter:

your credit

condition of the house

your down payment

if you have a principal residence already

number of units in the house

In short, no one can offer you quality guidance without knowing these things.