Ministries located in Canada must display their Canadian Charity ID and a signature on each contribution statement (Canadian donation receipt). To do this, insert your ID in the Regional Settings located at Settings --> Admin Settings --> Regional Settings.
After you have inserted your number, contribution statements will automatically display your Charity ID.
You also have the option to upload a signature to be automatically printed on each statement. Select the upload button (to the right of the Charitable ID field), then upload a lpg or png file of your signature.