Hi,
one method is known to make extremely soft silicone rubber, which can be as soft as a gel: use silicone oil instead of silicone "resin", and cross-link it using the usual "hardener".
Silicone oils exist in varied molecular length that result in varied viscosity. You can also mix a silicone oil with a "resin" in varied proportion to adjust the hardness of the cross-linked rubber.
Is that what you're looking for?