Baby Linhof, cut-film

As you can see from the above image, I use a small "mini-cut" paper trimmer, only 23cm, (9"), to create a small film cutting jig. This allows you a "safe" and "repeatable" system, (essential when working in total blackness.)
I devised a technique that relied on the setting of two "stops", (permanently positioned on the base plate), to allow for the two cuts necessary to complete the procedure. The stops show in the above image as white rectangles, (white cardboard), fixed with double sided adhesive.
I will first run through the usage procedure, and follow-up with some dimensions and sizes:

When you have removed the film from its envelope, you make sure the emulsion side is facing toward you by feeling the edge of film notches.
Place 4"x5" film onto trimmer bed up against lower stop; orientated, as in above image, 5" high.
Cut off 11mm strip, (x5" long). (see cut strip has fallen down), image actually shows the two cut pieces placed back to show the line of the final cut.
Rotate film clockwise 90 degrees, upto upper stop position.
Make upword cut to split film into two halves.

This has given you your two film pieces for placing into your dark slides.

Film Size:
The actual size of the DDarkslide film holder is 6.5cm x 9cm, so nominal film size = 64mm x 89mm

The 4" x 5" film is actually 100mm x 125mm, so you need to trim back the 100mm side to 89mm,
Therefore the lower stop is position 89mm back from the cut line. (leaving a 11mm waste strip).
(I have been using Agfa APX100)

The 125mm side is split into two equal parts, ie. 62.5mm wide,
Therefore the top stop is positioned 62.5mm back from the cut line.
Even though the split width is only 62.5mm, which is slightly less than the ideal width of 64mm, it works fine. You cannot afford to be much narrower than this, otherwise the film will not be retained within the grooves of the darkslide, (min. width 62mm).

The negative carrier, when designed for 120 roll film, will likely be unable to cope with your cut-film width of 62.5mm, since it is designed for film 61.4mm wide.
Therefore prior to printing the negative, you will probably need to trim a <1mm strip off the narrow width dimension, so as to fit the film within your negative carriers edge stops.