F2 is a repeater on Rattlesnake, output 154.965 WLG68
F3 is a simplex remote base mostly for paging from Squak and it seems to me it used to simulcast from either the courthouse or Harborview. 153.755 KBL995 unless there was a change.
F4 is simplex on the National SAR freq of 155.160 KQ5761
My info is a couple years old, but I am pretty sure it is still valid.
F1 is the VHF part of the King County Mutual Aid Repeater (MARS) repeater that TX I think is 155.19
Long ago, they sometimes called LERN F5 (155.37) but that never really caught on.
WSP became the lead agency for the LERN plan, so others quit licensing on it.
Unless something has changed recently the King County Search and Rescue Association (KCSARA) volunteer groups are assigned unit numbers in the 800 range, and operate via communications agreements with the KSCO SAR unit when on the KC freqs. Most of the groups had their own license on 155.160
820's used to be SPART, 830's ESAR, 840'S 4x4 RESCUE COUNCIL, ETC.
f you look up under King County Misc in the Database area on this site there is a list of current SAR freq in the Mutual aid section. Most pageing in now done via Alpha/Num system. Also not shown is freq for ESAR (47.46/47.50 simplex) and 4x4 (47.66) Several years both used to have remote Tx/Rx sites but I dont know if they are still functional.
You're correct about the unit numbering system, but since the voice pagers went away most of the IDs on the SAR radios are tactical callsigns. These are dynamic and will be assigned to units as they deploy. For example, an ESAR search team may simply be "Team 1" The 4x4 guys use an alphanumeric ID, for example, my last name starts with "W" so I was "William 1". Simple.
Here's what most fo the SAR folks have in their radios in one form or another. This is a basic template.
Ham "511" 145.11
4x4 Primary 155.175
Explorer Search and Rescue 155.325
Seattle Mountain Rescue 155.16
Seattle Mountain Rescue 155.205
Search Dogs 155.22
Search Dogs 155.235
Base Camp Support 155.235
Search Dogs 155.265
Pacific NW Trackers 155.28
Ski Patrol Advanced Rescue Team 155.295
Sno County SAR 155.415
Washington State SAR 155.16
Oregon State SAR 155.805