The design is the visual features of the RACK MOUNTABLE HARDWARE WITH SURFACE ORNAMENTATION shown in solid lines in the drawings, whether those features are features of one of shape, configuration, ornament or pattern or are a combination of any of these features in which: FIG. 1 is a front perspective view of the design; FIG. 2 is a front view of the design; FIG. 3 is a rear view of the design; FIG. 4 is a right view of the design; FIG. 5 is a left view of the design; FIG. 6 is a top view of the design; FIG. 7 is a bottom view of the design; FIG. 8 is a front perspective view of a first variant of the design; FIG. 9 is a front view of the first variant; FIG. 10 is a rear view of the first variant; FIG. 11 is a right view of the first variant; FIG. 12 is a left view of the first variant; FIG. 13 is a top view of the first variant; FIG. 14 is a bottom view of the first variant; FIG. 15 is a front perspective view of a second variant of the design; FIG. 16 is a front view of the second variant; FIG. 17 is a rear view of the second variant; FIG. 18 is a right view of the second variant; FIG. 19 is a left view of the second variant; FIG. 20 is a top view of the second variant; FIG. 21 is a bottom view of the second variant; FIG. 22 is a front perspective view of a third variant of the design; FIG. 23 is a front view of the third variant; FIG. 24 is a rear view of the third variant; FIG. 25 is a right view of the third variant; FIG. 26 is a left view of the third variant; FIG. 27 is a top view of the third variant; FIG. 28 is a bottom view of the third variant; FIG. 29 is a front perspective view of a fourth variant of the design; FIG. 30 is a front view of the fourth variant; FIG. 31 is a rear view of the fourth variant; FIG. 32 is a right view of the fourth variant; FIG. 33 is a left view of the fourth variant; FIG. 34 is a top view of the fourth variant; FIG. 35 is a bottom view of the fourth variant; FIG. 36 is a front perspective view of a fifth variant of the design; FIG. 37 is a front view of the fifth variant; FIG. 38 is a rear view of the fifth variant; FIG. 39 is a right view of the fifth variant; FIG. 40 is a left view of the fifth variant; FIG. 41 is a top view of the fifth variant; and FIG. 42 is a bottom view of the fifth variant. The broken lines in the drawings are included for illustrative purposes only, and form no part of the claimed design. In FIGS. 1, 2, 15, 16, 29 and 30, the shading indicates contrasting tones. Drawings of the design are included.