The Scorching Ray spell reads (PHB, p. 273; emphasis mine):
You create three rays of fire and hurl them at targets within range.
You can hurl them at one target or several.
Make a ranged spell attack for each ray.
On a hit, the target takes 2d6 fire damage.
The Metamagic Seeking Spell states (TCE, p. 66; emphasis mine):
If you make an attack roll for a spell and miss,
you can spend 2 sorcery points to reroll the d20, and you must use the new roll.
You can use Seeking Spell even if you have already used a different Metamagic option during the casting of the spell.
So, my question is: Can you use the Seeking Spell Metamagic on each roll of Scorching Ray?
Best Answer
No, you can't
The description of the Metamagic feature states the following:
That is a general rule which can be overriden by specific text. But the Metamagic option Seeking Spell doesn't entirely override it (TCoE, p. 66; emphasis mine):
The word "different" is the reason why it won't work. You can pair it up with a different Metamagic option, such as Empowered Spell or Quickened Spell. But once you have used Seeking Spell, you can't use it again on the same spellcasting, as it isn't a different Metamagic option.
As Medix2 pointed out in a comment on this answer, this is confirmed in the Sage Advice Compendium: