Fit measure to markup

[Gérard Degrez]

Hi,

For an orchestral part that I am typesetting, I want to put a markup (Poco 
rit.) 
over a silent measure, but the markup is wider than the measure. Is there a way 
to enlarge the measure so that it fits to the markup width?

Code:
{\clef bass
\key g \major
\set Score.skipBars = ##t
\time 3/4
\override MultiMeasureRest #'expand-limit = 1
R2.*7 | R2.^\markup { \italic "Poco rit." } |
\relative c'{a4\p\staccato r a\staccato c\staccato r c\staccato g\staccato
r d\staccato}
}

Thanks in advance,

Gérard