In application note AVR1012 (XMEGA A Schematic Checklist) Atmel states the following:
The Low-frequency Crystal Oscillator provides an internal load capacitance of typical 8.0 pF. Crystals with recommended 8.0 pF load capacitance can be without external capacitors as shown in Figure 4-3. Crystals specifying load capacitance (CL) higher than 8.0 pF, require external capacitors applied as described in Figure 4-4.
Whereas Figure 4-4 shows a crystal with two 22pF capacitors and the following note:
[The capacitor] values are given only as a typical example. Please refer to the crystal datasheet to determine the capacitor value
Now what do i do, if i want to use a oscillator with a load capacitance let's say 12,5pF? Would i use two external 4,5pF Caps in addition (That's atleast what i would assume from reading application note AVR042 (Hardware Design Recommendations)?