From Camie: 

The original treaties pose a challenge when trying to cite them, so here are some tips.

First, do your best to follow the Chicago style. In the manual, you'll find specific entries on treaties, government documents, and legal documents. Any of these will help determine what information should go in the citation, and in what order. You will notice a specific ordering of the title, the year signed, who the parties of the treaty were, etc. In the case of the numbered treaties, they also have regular publication information, as official government documents are published by the Queen's Printer in Ottawa. 

Second, the source of these particular versions are found on the Government of Canada website, where you might find more publication information. DO NOT CITE THE WEBSITE as the source of the treaty. They are published documents, so have all of the bibliographic information any other published document would have. Be sure to use that information.  https://www.rcaanc-cirnac.gc.ca/eng/1360948213124/1544620003549

Finally, you might find UBC's Legal Citation Guide helpful: https://guides.library.ubc.ca/aboriginal_treaties/citing

The reality of any citation style is that you cannot always find the 'right' answer; instead, you have to work with the standard formula of the style. 

For more information and resources, see the Library research guide to Citing Government & Legal Documents.