Yes. Think about it this was. Your RF out is like a radio transmitter. Without a load at the end, the RF is going all over the place including being reflected back into the generator.
Every work on a ham transmitter or hear of a dummy load? You're probably too young to remember token ring computer networks or you'd be all too familiar with termination.
I just solder a 47 ohm resistor between the test clips
Here are some ancient ones.
