I need to add another RRSP contribution to my tax return after my return has already been submitted

[Delphision · Accepted solution]

If you have opened a "My Account" with CRA, you can go online and change your return.  If not, you will need to fill in a T1 adjustment request, attach a copy of the slip and mail it in.

http://www.cra-arc.gc.ca/E/pbg/tf/t1-adj/README.html