Glyphs Glyph Info gives rehDotbelowdotabove-ar the components reh-ar, dotabove-ar, and dotbelow-ar. However dotabove-ar is not appropriate here as it will typically be placed above the reh (like in zain-ar), where in rehDotbelowdotabove-ar the above dot is placed inside it. First is good, second is bad:
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I think dotcenter-ar is probably more appropriate here.