When using external capacitors, the load capacitance (CL) is the total capacitance seen by the crystal across its terminals. It is calculated by the following equation.
C1 and C2 are ceramic SMD capacitors connected between each crystal terminal and ground. Cpcb1 and Cpcb2 are stray capacitance on the PCB. Cpin is the pin input capacitance on pins XL1 and XL2. The load capacitors C1 and C2 must have the same value.
When using external capacitors, the internal capacitor is disabled by setting OSCILLATORS.XOSC32KI.INTCAP to 0.