One male can reproduce with multiple females simultaneously, so get 1 male and a ton of females, that way you get fert and normal eggs. + because of the fert eggs, you have a better rate of getting eggs to make kibble.

If you can, search for a female rex and tame it. Much easier to get eggs rather than follow her around

If you're in singleplayer and you throw away or remember years ago that you threw away a "rockwell recipes: easy bird kibble" after completing the keep your distance pursuit then that's your misfortune as only one can exist per player as the game gives you the item after you obtain all the ingredients for rex kibble so if you throw it away you lose it forever.

if you playing on mobile especially old ark, u need prime jerky, longrass, rex egg, mejoberry, water, and fire it with sparkpowder in cooking pot. congrats now u have rex kibble in ark mobile.

You can tame one then let them mate and then watch until it lays then after that you can get so much more