Think this is your Rothsay from Manitoba Vital stats.

Last Name: REID
Given Names: ROTHSAY MONTROSE
Sex: FEMALE Date of Birth: 13/10/1909
Place of Birth: BRANDON
Parents Married: YES
MOTHER'S DETAILS Maiden Last Name: MCLEOD Given Names: JESSIE

Will note in this record says they are Female but in the 1911 census of the family in Winnipeg the transcript list as Male. I did not view the actual census record to see if it is a transcript error or not.