The combinations are okay, but unless it has family significance, I'm not fond of the offbeat spelling of
Kathryn. Also, be sure you want your daughter to have the initials O.K. (Smith or whatever) -- sounds like a Fort Worth used car dealer.
And check the
Seth name against your last name, to avoid initials like SAC,
SAD, SAG,
SAM, SAP, SAT. You get the idea...
- Da.