The rapper pulled up in his expensive Rolls-Royce Phantom on Thursday right outside the Burberry and Louis Vuitton stores in Beverly Hills, where he started throwing wads of cash in the air. It wasn't long before a throng of fans -- of the rapper and money, of course -- showed up to catch it.

Our guy asks him how much he's throwing but it's hard to tell if RTK gives a direct answer. He wishes a woman happy birthday before pulling out another wad of bills.

Then, things get interesting ... for Rich, anyway.

You can see near the end of the video he's taking a selfie and 2 police motorcycles pull up behind him. RTK's driver takes off ... and the cops follow right behind him. We never saw the sirens and lights go on, but our law enforcement sources tell us Rich did end up getting a ticket ... for littering. That's gonna cost him a few more dollar bills -- minimum $250, max $1,000 for a first offense.

BTW ... Rich was definitely in a celebratory mood 'cause we're told he had just been inside the Patek Philippe store on the eve of dropping his new track, "Richard Mille Patek."

As for the Phantom, we're told it's a brand new model and around $600k. Rich was cruising around town with his buddy, RD Whittington, who owns celebrity auto and aircraft super-firm Wires Only ... so you gotta imagine he helped hook him up.