Here’s an advertisement from the November 8 1933 edition of the Toronto Daily Star for a treatment that claimed to cure baldness.
Charles Nessler, also known as Karl Nessler (1872-1951) was an inventor of a commonly used method of creating a permanent hair wave (at least according to his Wikipedia page, which is somewhat flattering to him). His original treatment method apparently consisted of cow urine and water. He eventually opened a chain of hair salons in the United States and became wealthy.
I could find nothing on the Pro-Ker Hair Treatment or the Karascope in searches. I’m not sure how a permanent wave can cure baldness, since I assume that it works with the hair that you already have. But I don’t know enough about it. This Wikipedia page describes the history of permanents in considerable detail, if you are interested.
I traced Raymond Harper in the Toronto city directories, because why not. Before becoming associated with Pro-Ker Hair Treatments, Mr. Harper had been working as a manufacturer’s agent, with space in the office building at 319 Bay Street. The 1934 city directory lists him at both 319 Bay and in his new space at 67 Yonge; after that, he focused on baldness and the alleged prevention of same.
The Pro-Ker Hair Treatment system turned out to be Mr. Harper’s life’s work. He remained its manager right through 1950, though the 1943 directory listed him as a technician for the Ontario provincial department of health. I’m not sure whether this was a temporary stopgap due to the war; the directory still listed Pro-Ker Hair Treatments at 67 Yonge, so perhaps Mr. Harper was taking on a side gig due to a wartime-related shortage of people interested in hair treatment.
By 1951, he had passed away, as the directory lists his widow, but Pro-Ker Hair Treatment soldiered on, now under the management of Alfred E. Harper. His address was the same as Raymond Harper’s widow, so I would guess that this was the son taking over the family business. He stuck with it, too: his office moved to 2 Bloor Street East in the 1950s, but it was listed in the 1964 directory. By 1966, though, it was gone. The junior Mr. Harper remained in the directory, but with no listed occupation; perhaps he had retired.