wild duck, end, suffix
鳧 centers on a wild duck. The meanings 'end' and 'suffix' appear to be unrelated or possibly from a different usage context, so treat them as separate, less common senses.
鳧 combines 鳥 (bird) and 几 (table or stool), but the exact historical origin is uncertain. It may have originally depicted a specific type of waterfowl, with 几 possibly contributing a phonetic element.
A bird (鳥) standing on a low table (几) by the water's edge: that's a wild duck resting before taking flight.
For フ, imagine a wild duck letting out a soft 'foo' sound as it lands on the table: foo -> フ.