Not sure why it isn't listed in there but BL rune cost modifier is 2.0 ... I am going to check out the numbers for KR a little later today.
The Ritual page in general needs to be updated for 73, I would like to see the spell cost modifier listed there, or at least in a separate section of the chart on the Mystic formulas page, if not both. As well there is a minor typo on the Ritual page near the top "The Monarch or Steward can being a ritual"
Also, are all Rituals the same cost to cast? Update; Barrier, at least, is a 6x rune cost multiplier