No, I don't think you need to know what KIND, but you surely have to know it WAS a rattler.
Just "some kind of bite" don't cut it, when considering anti-venin.
I'm sure there was more to the story.
Could have been a cobra. People are collecting them these days.
Yuck
Out here when the fire department is called to remove a rattler, they always ask what kind before they leave the station.