There are different ways this can be done:
You can change the practitioner's access level to clinical or full access.
You can share notes within Clinical Notes: on the patient's Clinical Notes screen, click the blue triangle button and select Share. You will be able to share the selected note with the patient or with another practitioner in your practice group.
You can add the practitioner to the patient's General page under Practitioner Relationships and selecting the level of access they can have.
NOTE: if everyone in your practice who is eligible for sharing the file already has access (including by having full access), the option to share the file will be greyed out.