Why is the ILS16 approach at KSKF not available in my Garmin 430W?
There are two ILS approaches for runway 16. Both of them had amendments on 13 Aug 20. Therefore, the IAP charts that were in the database are no longer valid. They expired. It would be interesting to know the effective date of your last Garmin update. That could affect what approaches you are able to see.
I am unable to pull up the former IAP charts at this time. It would also be interesting to see what has changed. At the KTKI airport, the decommissioning of the MELISA NDB was enough to require a complete change of the ILS approach. Melissa was the Final Approach Fix. You were to notify ATC when you were Inbound inside of the FAF. The NDB has been replaced by the JIPUK waypoint.
This is a good lesson for new pilots. Read the entire IAP chart (including the borders) and check the effective dates.