Most probably from *rayyəm, as a hypercorrect reaction to the sporadic shift z > y in Amharic (for which see Podolsky 1991:44). A further hypercorrect development is found in the verb räzzämä ‘to be high, tall, long’ (AED 404)
Amharic
säḳäṭ, šäḳäṭ - goods, merchandise, thing sold at retail
(AED 511, 632)