yes, simply mix a little repair bag of sand and cement - plumbers, and builder's merchants carry them - and point up where its missing.
from the pic there's no need for dye.
the gutter seems to be fixed in a cocked-up position? is this causing any water overflow problems?
Using sand and cement I already had, made 3:1 mix which is recommended for tile pointing and got a 1kg of Red Everbuild Mortar Tone, mixing it in to get a near same mortar colour to match.
There's places where its cracked and detached so I've pulled it out and will re-point.
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great, get stuck in, & do all faulty looking pointing at the same time.
thing is, its usually best to lift the tile when pointing up more than a few cracks - lift and clean off any residue mortar.
you have a good projection from the undercloak, and all edge tiles appear to be clipped which is also great.
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