As this post shows, you "can" purchase thru your broker. However, if someone calls tomorrow, they likely will not have the details yet, especially since it's not even priced! No worries though since the price will be "fixed" once set.
Also, unless broker gives you the option to purchase without assistance (the regular way people buy/sell) they should NOT charge you the extra "broker assisted" fee. You may need to "tell them that"! Finally, depending on who answers the phone, they may try playing dumb & tell you to call RHK. You're the customer so just THEM to get the details & call YOU back & they will.
I've been thru a similar process (Units, warrant exercise) & it really is straight forward & easier than it may appear.