I know PK means primary key and FK means foreign key, but

what do "rK" (in section 3) and "PF" (in sections 3, 4, 6, 7, and 8) mean on this page? http://www.databaseanswers.org/tutorial4_data_modelling/index.htm

And what does "FF" mean (in the Customer_Addresses table) on this page? -I'm new so it would only let me put in one hyperlink, so copy/paste this to go to the page I'm asking about:

databaseanswers.org/tutorial4_db_schema/tutorial_slide_7.htm

Thanks.

Edit: also, I understand the concepts of primary keys and foreign keys, but what are these other ones used for?