Mythic rules question on Abundant Casting and Scorching Ray

[Dovahkiin62]

I'm having some trouble explaining to a player why the Archmage path ability, "Abundant Casting" does not work with "Scorching Ray"

According to the path ability description for Abundant Casting, "Whenever you cast a spell that specifically targets a limited number of targets (such as “one creature/level” or “one or more creatures”), add your tier to the number of targets the spell can affect."

My player has taken this to mean that he can fire off 2 additional bursts of Scorching Ray (thanks to his 2 mythic tiers), making for a total of 9 rays fired.

My understanding is that this shouldn't work as the spell isn't "targeting" a specific number of creatures, but manifesting bolts of fire that the caster can direct at will. For Abundant Casting to work (again, by my reading), a spell has to list in its descriptors something like "1 target/Caster level", and Scorching Ray doesn't have this descriptor.

I've tried to explain this to my player, but he is confused by my explanation as he is still "targeting" creatures with his scorching rays.

So, Hivemind, can you please advise how I can more clearly explain my reasoning? Or else clarify if my reading of the ability and spell is incorrect?

[Lotheb]

As far as i can tell your reading is correct. In terms of explaing: have you shown them an example of spell that does have a targets entry? Haste is the first one i can think of.
Alternatively/additionally point out that you can target objects or points in space with Scorching Ray.

[Warchon]

Your explanation is both succinct and clear, and your reasoning is sound.
However it does sound like his interpretation is REASONABLY close to RAI and two more Rays on top of the already ungodly number provided by his epic level isn't a huge power jump, barring extreme metamagic shenanigans.
Depending on the player's history (does he tend to try to slip crap past you), his power level relative to the rest of the table, and whether or not his confusion is genuine as opposed to just being stubborn, you might be better off just making the call of either

"I'm going to allow it but be aware that it is a house rule and I might rescind it if things get ridiculous"

Or

"That's my interpretation and you're going to have to live with it."

[DarkSoul]

Show him the spell description for scorching ray, and for haste. Explain that haste has a "targets" line in it's spell entry while scorching ray does not. Abundant Casting adds to whatever is listed in the "targets" line. If there's no line to modify, as with scorching ray, then Abundant Casting doesn't apply.

EDIT: Yeah, what Lotheb said.