TCR lists H&C(RHC) for the $25. The one on The Chip Guide (see below) shows house mold (TCR E4957).

There's also a current ebay auction listing the $100 chip with a house mold.
http://www.ebay.com/itm/Unlisted-100-South-Coast-Las-Vegas-NV-Casino-Poker-Chip-Obsolete-Scarce-Rare-/181350553020?pt=LH_DefaultDomain_0&hash=item2a3955d5bc

The place operated only a year or so under South Coast name. Maybe not many high denominations collected (or seen?). TCR does show House mold for the 500, 1000 and 5000. It also has a year later date on "Date" for the higher denominations. Could be it took a few months to get the tooling made for House mold?

Maybe a correction needed?