I use a Marbles Standard Tang sight on mine (as well as on all my other lever guns).
Marbles lists part number 009807 for the standard tang sight for the Rossi 1892, with screw set 995002, although I've used the 009808 sight for the Winchester 1892 and 1894 on all of mine. The tang is a bit longer on the Rossi 92 than on the Winchester, or the Armi-Sport copy of the 1892, and that may be the difference.
Both sights use a hole spacing of 2.000" to 2.265", and I use the Lyman No 2 tang sight spacing to allow me, or future owners to use either sight without drilling a second hole.
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The primary advantage of a tang sight, over a receiver sight or barrel mounted aperture sight is that the small aperture placed reasonably close to the eye (a few inches in this case) effectively increases the depth of field of your eye and allows you to focus on the front sight. With a receiver sight the effect is reduced and with a barrel mounted aperture, you won't see either sight element clearly with middle aged or older eyes.