I don't actively pursue RFPs and have decided not to bid on them when invited. For the most part, I find that the elearning RFPs lack enough information to make a proper bid or they ask you to jump through hoops just to get to an interview stage.
Having said that, I know you are based in Ontario so you could try
https://www.merx.com or
http://www.rfp.ca for public sector opportunities. You can also try city websites such as
https://web.toronto.ca for municipal opportunities.
Some of these sites make you pay for the RFP so you have to decide if it is worth it or not and since most seem to be geared towards big vendors or have a vendor of preference (and they are just going through the motions) it is most likely a long shot to submit a bid.
As for private sector RFPs, I am not sure if there is a centralized site or not. My suggestion would be to monitor the companies you are interested in and also to visit the Job Postings section on this site on a regular basis because companies sometimes post requests for proposals.