The RKx series of TACT switches recently introduced by C&K have the perfect form factor and actuation force for keyfob or hand held applications.
The RKA series offers a 4.5mm X 4.5mm with a slim profile, down to .55mm height and an actuation force of 260, 400 or 600
The RKB series offers a 4.6mm X 3.2mm with a 2.5mm height.
The RKC series offers a 3.5mm X 2.6mm with only a 1.44mm height and an actuation force of 450.
All these series offer a operating temperature range of -40C to +85C
For more information on these, or any other C&K product, go to www.ck-components.com