Currently, Sage 100 does not support Multi-Currency without enhancements.

https://www.dsdinc.com/enhancements/marketplace/search?group=multi-currency

An alternative would be to create a Canadian invoice template and add CAD field to it.  This would require a CAD UDF in the SO/Invoice header for the translation rate.  The template CAD field on the line item would use the translation rate field to calculate the CAD amount.  Of course there would other fields as well but you can see where this is going.  There is a little bit of set up involved but if you don't have a LOT of CAD invoices, it is an alternative to the enhancement route.

Indeed, the enhancements wouldn't be worth it for a small number of transactions, but keep in mind that manipulating the form to print a CAD translation of the invoice doesn't help with the Cash Receipt side.

I think a few of our clients set up an AR Division as a different currency, and do month end adjustments to handle currency exchange for the purpose of financial reporting... but I'm not an accountant so I don't know how that is done.