PCS

*rkk - to be tender, soft, slender (Kogan 2015: 197)

Hebrew
rkk - to be soft (HALOT 1236)
Syriac
rkk - to be soft, tender (LSyr. 730, SL 1469)
Syriac
raḳḳīḳā - thin, slender (LSyr. 743, SL 1489)
Turoyo
raḳiḳo - dünn (thin) (RW 436)
Arabic
rkk - to be weak, feeble (Lane 1141)
Jibbali
rekk - to be poised to fall; to shake something till it is ready to fall (JL 211)
probably an Arabism
Jibbali
rɔ́ttək - to be moved, shaken loose; to be loose (JL 211)
probably an Arabism