Kathleen Barr also voiced Rudolph in the 1998 Rudolph the Red-Nosed Reindeer: The Movie (1998) 2D Animated movie, released 3 years prior. Both films were recorded in Vancouver, Canada.
This a CGI sequel from Rudolph The Red nosed Reindeer: The Movie though it was used for Rankin-Bass characters.
Even though Rudolph's gender is male, he has always been voiced by a female.