[Groff] Different font in first line of paragraph

[Dirk-Wilhelm Peters]

Hi,

is there a robust way to switch to a different font after the first
line of a paragraph is adjusted? The example below comes close,
but the first word of the second line of the paragraph is already
typeset in the previous font.

.ll 4c
.de PP
.br
.ft B
.wh \\n(nlu+1p DF
..
.de DF
.ft R
..
.PP
This is just an example paragraph.
It should be formatted in a different
font in the first line.