There is a
Minhag*, not to face the בעל קריאה
(standing in front of the בימה) when he Leins (reads)
*Another Minhag is that the עולה before the
the בימה immediately after his Aliya and doesn't wait for
end of the next Aliya to do so.
In some Shuls during the year when the Gabai wants to
give an Aliyah to the בעל קריאה he doesn't call him up
by saying יעמוד פלוני ב"פ since he is already standing
All he does is point at him to take the next Aliya.
Hence this is how the Minhag started for the בעל קריאה
to get the תוכחה since there is no need to call him
**The original Minhag was to put it in the contract
the שמש needs to take the Aliya of the תוכחה.
The רמ"א writes to call up יעמוד מי שירצה (no name)
is willing to take this Aliya.
The מקור חיים writes that the מי שירצה is a חיוב to be
on the first day Rosh Hashana and on the first day Shavuos.
ie: The מי שירצה is being compensated by getting
on the first Yom Tov after the תוכחה