In RADKFILE, the only radical 暇{ひま}, 霞{かすみ} and 蝦{えび} share is 又. It doesn't have anything for the two other distinct parts of 叚.
I haven't seen the parts in other kanji, except that the left one looks a bit like 尸 with two additional strokes and the top right one looks like the katakana コ (which was derived from 己).
What are they?
As snailplane said, RADKFILE is not a source of information on the history of kanji components, their hierarchical decompositions, or their original rationale.
The origin of 叚 is unclear. Its old meaning is "false", "provisional", and 又 is a pictograph for the right hand, often grasping something (indicating tool use, actions, etc.):
You can see in the early forms of 叚 that コ probably comes from another hand, facing the other way (the kind that in most kanji resulted in a ヨ shape):
The left side seems like some sort of cover or container with horizontal markings inside. According to Tōdō's interpretation this could be showing the act of "hiding" items, related to them being "false". Sears thinks it's "a hand with a flint knife striping a skin off an animal", but that feels like a stretch to me; though other people (like Harbaugh) also connect the left part to an altered "skin" (皮). Shirakawa thinks it's an unpolished jewel cut off from a mountain, but Shirakawa is insane and basically always wrong. In summary, there seems to be no consensus.
Since all of 暇蝦霞假瑕葭遐碬豭赮騢 are pronounced カ (with 蝦霞碬赮騢 also sharing ゲ and 假碬豭 ケ), the common presence of 叚 in them is certainly for phonetic reasons.
(All images from Sear's Chinese Etymology website.)
The original meaning is not universally agreed upon, but the structural composition is not ambiguous. The earliest form of 「叚」 is comprised of 「石」 on the left and 「又」 on the right.
Please refer to What is the etymology of the kanji 石? for a more detailed overview of「石」. Key points:
- 「石」was originally a picture of stone chimes.
- 「口」was not present originally, being added as a distinguishing component to mark the name of a region.
- What looks like a cover「厂」in later forms was a graphical reduction of the stone chime shape.
- The two horizontal marks that appear in some forms are decorative (Chinese: 飾筆), and don't contribute to any semantic or phonetic function (decorative marks are also seen in modern forms of many characters like「魚」and「甚」).
Afterwards, 「刀」 was added to the top-right. The modern form of 「叚」 should be seen as composed from 「石」 (left, inherited from a form with decorative marks and no 「口」 ), 「刀」 (top right), and 「又」 (bottom right).
Here you can find the meaning or the relating information.
