Short answer. At least one witness. Rule 76, Section 5 requires that, for an uncontested holographic will, at least one witness who knows the testator's handwriting and signature explicitly declare that the will and the signature are in the testator's handwriting — and if no such competent witness is available, the court may resort to expert testimony instead.
What the law says
In the case of a holographic will, it shall be necessary that at least one witness who knows the handwriting and signature of the testator explicitly declare that the will and the signature are in the handwriting of the testator.
Rule 76, Section 5 — Proof at hearing. Read the full provision →
What the law says
If no person appears to contest the allowance of the will, the court may grant allowance thereof on the testimony of one of the subscribing witnesses only, if such witness testify that the will was executed as is required by law.
Rule 76, Section 5 — Proof at hearing. Read the full provision →
What the law says
In the absence of any such competent witness, and if the court deem it necessary, expert testimony may be resorted to.
Rule 76, Section 5 — Proof at hearing. Read the full provision →
One witness is enough for a holographic will, uncontested
Rule 76, Section 5 states that, for a holographic will specifically, it shall be necessary that at least one witness who knows the handwriting and signature of the testator explicitly declare that the will and the signature are in the handwriting of the testator. This is a lighter requirement than what applies to an ordinary attested will, where a subscribing witness testifies to the will's due execution — for a holographic will, the focus is squarely on someone confirming the handwriting itself.
The general uncontested-will rule this sits inside
This holographic-will provision sits inside a broader rule covering what is sufficient when nobody appears to contest the will: if no person appears to contest the allowance of the will, the court may grant allowance thereof on the testimony of one of the subscribing witnesses only, if such witness testify that the will was executed as is required by law. For a holographic will, the specific handwriting-and-signature declaration takes the place of that ordinary subscribing-witness testimony.
If there is no such witness at all
The rule also covers what happens if you cannot produce even one competent witness who knows your relative's handwriting: in the absence of any such competent witness, and if the court deem it necessary, expert testimony may be resorted to. This lets the case proceed even without a witness who personally knew the handwriting, though it is framed as something the court resorts to when it judges expert testimony necessary, not an automatic entitlement.
Compliance still has to be shown at the hearing
Before this testimony is even introduced, Section 5 requires that compliance with the preceding sections' requirements be shown at the hearing, and that all testimony offered in support of the will be taken under oath and reduced to writing. The witness's declaration about the handwriting is not simply accepted informally — it has to be given as sworn testimony, on the record, as part of the hearing on the will's allowance.