any bank, just go to the same bank you have your account in, and ask them to make a demand draft. and make sure that you use the payable name as Receiver General in canada. all the banks can make the same kind of the draft.
In KSA best rate in CAD Dollar AlRajihi bank, other bank also making Cad $ draft like SAAB bank , NCB.
We went many bank it is not so easy and all banks are not having in CAD Dollar, so please check only AlRajihi or SAAB Bank in Jaddah. and in the favor of Receiver General Canada.