ASR-F forms are conveniently located in the stationary wallet inside the cockpit.
A fillable PDF version is also available for download on the appropriate website.
And now, a few words from the gospel of OPS-A 11.9.1:
Thou shalt submit an ASR-F to proactively report a fatigue risk, and thou art encourageth to submit same if thou hast found thyself guilty of exercising the sin of controlled-rest. Amen.