Riders extend a base policy with targeted protections — Accidental Death Benefit, Critical Illness, Premium Waiver, Term Rider, etc. They are priced separately and added to the base premium. Rider premiums do qualify for §80C (subject to the overall ₹1.5 L cap and the 10× SA rule on the rider's own SA).
When calculating the implicit XIRR of a participating endowment, rider premiums should be excluded from the cash-flow base — riders buy protection, not yield, so mixing them deflates the savings return artificially.