Plate looks right to me, Lalique 'Epis', one of the earliest press moulded pieces introduced c. 1921.
The script signiature does look a little unusual though marks vary on this pattern. Early examples were signed with the moulded VDA (Verrerie d'Alsace) mark, used by Lalique in the first couple of years of operation of the Wingen sur Moder Plant, c.1921-3. I have seen one or two examples with the VDA mark & engraved signiature and seem to recall seeing ones just marked in script or with a moulded R Lalique to the top surface.
I have researched this pattern in the past after having seen VDA marked examples miscatalogued as just 'French glass plate' or similar. I have always hoped to get a bargain but so far others have also spotted them and I've been outbid Sad
Since then I had a look at a couple in a dealers in Chester (which i think has now closed) and at various auctions. Rago sold a nice example with a green patina in 2002 and reference it as Marcilhac p.753 no. 3235http://www.ragoarts.com/results_2002_10LA02.php