'slightly press' is correct and usable in written English.
For example, you can use it when talking about applying pressure or force in small increments: "He slightly pressed down on the accelerator and the engine revved louder."
Sometimes, after a while, almost imperceptibly, she began to press, just slightly press.
Just slightly press the sandwich.
Slightly press the brinjal with the fingers.
While straining the liquid, slightly press the ingredients in the strainer with a spoon to squeeze out the remaining liquid.
Buy some prepackaged cake pops from your nearby bakery and slightly press them to give them a semi-flat oval shape so that they look like Kitty's head.
To help keep the guitar in tune longer, let this helical coil top slightly press on the string section (end) that comes out of the opening of this tuning peg rod to reduce string slippage.
The samples from one of the set were placed between two stainless steel plates, and the last ones were slightly pressed.
Strong adhesion as high as 6.95 ± 0.92 MPa can be achieved when glass substrates deposited with LbL assembled PAH-D/HA films are slightly pressed together.
The fingertip shape was placed on the test equipment and slightly pressed in the normal direction of Δ h from the initial height by the micrometer, as illustrated in Fig. 1 a.
*The adorable lead singer's shirt was slightly pressed like he'd picked it up from the cleaners and yet he still wore it in a laid-back, pass me the carafe, way--a clean, casual, style belonging to the French.
After 45 min incubation in the dark, the stamp was dried, immediately placed in contact with a glass coverslip (Marienfeld) and slightly pressed with tweezers for several seconds.
